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Entered, According to Act of Congress, 

'In the Year 1849 , 

BY PETER VON SCHMIDT, 

In the Clerk's Office of the Southern District of New-York. 


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THE 

YOUNG ASSAYERS’ 

AKD 

MINERS’ ASSISTANT, 



PETER VON SCHMIDT, 

CIVIL AND MINING ENGINEER; 

COMPILED FROM THE BEST AUTHORS 

ON CHEMISTRY AND GEOLOGY, 

FOR 

the express purpose as a guide for persons who 

WISH TO EMPLOY THEMSELVES TO RECOGNIZE, 
ANALYZE, AND ASSAY, METALS AND 
ORES OF ALL KINDS, 



NE W-YORK. 

^ 6. W. PALMER, PRINTER, 122 NASSAU-STREET 











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PREFACE. 


1 Hi.s little work contains the principles from which 
may be discovered, from superficial appearance, weight, 
and other properties, any ore or mineral under exami¬ 
nation, and by analysing or essaying, to find out their 
true value. 

There are, it is true, many valuable books on the sub¬ 
ject, by eminent chemists, but they are too voluminou.s 
and expensive for those who are practically engaged in 
discovering the hidden and inexhaustible treasures ol 
our country. Here, the compilation has been made 
with care, and the object has been to concentrate, select 
and extract only such parts as are deemed most useful 
to those engaged in searching for metals and ores. To 
farmers, miners and travellers who are without the 
chemical or geological knowledge, it will be important, 
and probably induce explorations that may‘result to 
their advantage. 


THE AUTHOR. 


LUTES FOR SECURING JOINTS. 


For Water^ Alcohol^ Ether, ifc .—Slices of moistened 
bladder,, or of paper, or linen, spread with flour paste, 
white ol egg, or mucilage of gum arabic, or of almon- 
meal, mixed to the consistency of glazier’s putty, with 
water or mucilao'c. 

OF ACIDS OR HIGHLY CORROSIVE SUBSTAN- 

CES. 

Fat Lutes, formed by beating pei'fectly dry, and finely 
sifted tobacco-pipe clay, with painter’s drying oil, to 
such a consistence that it may be moulded by the hand. 
The same clay, beat up with as much sand as it will 
bear, without losing its tenacity, with the addition of cut 
low, or of horse-dung, and a proper quantity of water ; 
it resists a imnsiderable heat, where a fat lute would be 
destroyed. 

To protect the retorts from too sudden change of tem¬ 
perature by coating : 

For Glass Retorts. A mixture of moist common clay, 
or loam, with sand, and cut tow or flax, if the distillation 
be performed by a sand heat, the coating needs not to bo 
higher than the bedding of the Retort in sand;—but if 
pcrlbrmed in a wind furnace, the whole body of the Re¬ 
tort, and the part ol the neck exposed to heat, must be 
carefully coated. 

Earthen Retorts are better adapted ; they may be cov¬ 
ered with a composition of two ounces of borax, dissolved 
in a pint of boiling water, and slacked lime added, to the 
thickness of cream, to be applied by a painter’s brush, 
and allowed to dry. Over this, a thin paste is afterwards 
to be applied, formed of slacked lime and common linseed 
oil, well mixed, and perfectly plastic, let it dry a day or 
iwo before use. 


6 


OF itfiDtJCING GOLD. 


To Join Iron Vessels used in distiation, a mixture ot 
the finest China clay, with solution of borax ; 

The above named lute of clay, flax and sand, may also 
be used. 

N. B. In all cases the lutes must be perfectly dry be¬ 
fore the operation. 

FLUX. 

Black Flux is prepared by deflagrating cream of tartar 
with half its weight of nitre. 

White Flux by a similar process, with twice its weight 
of nitre. 

Silver Flux, to one part of ore, after washing and roast¬ 
ing, add one part of glass of lead, made by melting lith¬ 
arge with half its weight of calcined flint, and twelve of 
granulated lead, to be added to it, and then the process 
of scorification and cupellation as usual. 

Stones for Silver, or assaying various kinds of Earth. 
One part of it is to be mixed with one part of glass of 
lead, then scorified and cupelled with twelve parts of 
granulated lead. Or these three ingredients are mixed 
together in equal parts, covered with common salt, and 
brought to perfect fusion. 

REDUCING GOLD. 

Nitro-Muriate of Gold, to be diluted three times with 
boiling water, and a solution of very pure green sulphate 
of iron, is poured into it. The precipitate of gold is 
washed upon a filter, along with a mixture of equal parts 
of nitre and horax. 

Potash and Soda, throws down a precipitate of Nitro- 
Muriate of gold, of a yellow powder—by excess of alcali 
it is again redissolved—the precipitate takes place only 
by a boiling heat. 

j1 Solution of very pure green sulphate of iron reduces 
gold entirely to the metallic state ; this is the re-agent by 
which gold is most completely precipitated from its solu¬ 
tion. 

A Solution of Tin in Nitro-Muriatio acid, prepared so 

to be in a low state of oxidation, throws down a pur- 


NITRO-MTJRIAXIC ACID. 7 

• ‘ I > 

pie precipitate. This is a compound of the oxides of the 
two metals. 

According to Murray, two parts Nitre and one of Mu¬ 
riatic acid dissolve gold rapidly. 

Diluted Nitric Acid^ Solvent for Silver. The solution 
is first greenish, soon disappears, becoming colorless if 
the silver is pure. Nitrate of silver is reduced by one- 
part of the sub-carbonate of potash, to four parts of the 
muriate, by a red heat in a crucible. This is the best 
process to obtain pure silver. One hundred grains afford 
seventy-five of metal. 

From Nitrate of Silver potash throws down a yellow¬ 
ish precipitate ; soda and lime ammonia, gray or black. 

Copper is employed to recover silver from its solution 
in nitric acid, to obtain it free from other metals, the lit¬ 
tle copper being removed afterwards by cupellation. 

Silver is removed from its intermixture with copper by 
boiling them in sulphuric acid—the sulphate of copper 
which is formed, being removed by washing, the sulphate 
of silver remaining insoluble ; or employ a mixture of 
sulphuric acid, and nitric acid, it dissolves silver without 
dissolving copper. 

Platina in Solution is precipitated by a solution of mu¬ 
riate of ammonia, a precipitate is thrown down of oxide 
of platina. On urging this precipitate with a tire, gradu¬ 
ally raised to an intense degree, a spongy metallic mass 
is obtained, which, while hot, may be made denser by 
hammering. 

Taste for Copper Ores. Water of ammonia digested 
upon any cupreous ore in a pulverized state, after they 
have been calcined, either alone or with nitre, assumes 
an intense blue color, indicating copper. 

NITRO-MURIATIC ACID, OR AQUA REOIA. 

Take muriatic acid (1.15), and nitric acid (1.34) 
parts by weight muriatic, and 20 parts of nitre, after 
effervesence ceases, keep it in well corked bottles in a 
cool and dark place. 

Platina in a Solution of Gold. Pour into it a solut ion 
of sal-ammonia, which precipitates the platina alone— 


B separating gold from silver. 

after which the gold may be thrown dow separately by 
copperas water, (sulphate of iron.) The gold powder, 
or precipitate is mixed with a little salpeter and melted, 
the salpeter separates any portion of copper contained in 
it. The blue solution left after the preciptate of the silver, 
being a solution of copper—may be evaporated and crys- 
talized. 

Gold Ore's Assaying. There is properly no assaying 
of ores of gold. The silver ores that contain gold, are 
first assayed for the silver they will yield, and if this is 
sufficient to paj’' the charges, they are smelted and cup¬ 
elled, and the silver thus obtained is assayed for the 
gold. 

Gold Dust., is assayed as gold itself, which holds a little 
.silver or copper, by first cupelling a portion of it with 
lead, as in assaying silver, and then flattening the bead. 
By these means the gold is obtained from poor gold, 
holding metal, b}* means of sulphur and litharge, as 
already related ; also from the native gold dust collected 
from the sands of rivers, and from old gold plate, coins, 
and trinkets of that metal. 

If gold contains no silver, which is rarely the case, 
cupellation alone, with a proper quantity of lead, as in 
the case of silver, is sufilcient, but if the metal contains 
.silver, it is first to get rid of the copper and lead by 
cupellation, and then manage, that the metal may con¬ 
tain one quarter in weight of gold, and three quarters of 
silver-, this is called quartation. If the silver is in too 
large quantity', part of it must be removed by means of 
.sulphur, and if too small, a sufficient quantity of pure 
silver must be melted with the metal, and then the 
quarted metal may be parted with aquafortis. 

Gold which has been equarted, is separated 1‘rom silver 
it contains, by parting with aquafortis. In a large way 
it is melted, and ladled out with a small three-cornered 
crucible, it is poured in a fine stream into cold water, 
and thus reduced to grains. 

About six pounds of this granulated gold is put into a 
glass bolthcad, the bowl of which is coated with clay ; 
and placed in a sand bath, aquafortis is poured in, so that 
the gold is entirely covered. A gentle heat applied, and 


SEPARATING SILVER FROM GOLD. 


9 


when the Aquafortis appears to be saturated, it is drawn 
off, and fresh Aquafortis poured on, until it has no action 
on the metal. The fire withdrawn, and when the fur¬ 
nace is cooled the remaining Gold is washed with hot 
water, until the water comes off tasteless ; the washings 
are collected together in a copper basin, and salt added 
to separate the Silver it contains, as Muriate ol Silver; 
the washed Gold is carefully dryed, melted with a strong 
fire, and cast in ingots ; it is twenty-three carrats eight- 
twelfths fine, and very ductile. 

The Aquafortis that is drawn off, is distilled in glass 
retorts, and which operation lasts several days—the fire 
is at first very gentle, when red vapors appear, the ap¬ 
paratus is luted, and the fire increased. Towards the 
end some Nitrate of Silver sublimes in whitish flowers, 
adhering very fast to the neck of the retort. The distil¬ 
lation being finished, the retort broken, the flowers and 
glass to which they stick are melted with a little 
Litharge, and then a button of Silver is obtained. The 
residue of the distillation is carefully collected, and to¬ 
gether with the button just mentioned, is added to the 
lead obtained in remelting the Sulphuretted Iron, arising 
from separating Sulphur from Silver by Iron, and cupel¬ 
ed as already stated ; the product is fine Silver. 

- As the Silver obtained by cupellation from the Lead 
and Copper Ore contains a very minute portion of Gold, 
this is separated by means of sulphur or dry parting. 
The Silver is melted 100 or 150 lbs. in a black melting 
pot, kept melted two hours, ladled out with a small cru¬ 
cible, and poured into cold water kept stirring. The 
Silver thus granulated is distributed into wooden dishes, 
and dusted with one-eighth its weight of Sulphur, the 
grains are then shaken to distribute the sulphur equally. 

On remelting this Silver it divides itself between the 
Sulphur and the Gold ; the Sulphuretted Silvgy swims at 
top of the Alloy of Gold and Silver. When the mass is 
perfectly liquid, about one-sixteenth or one-twelfth of 
Litharge is strewed on the surface; the Litharge is re¬ 
duced, and part of the Lead unites wnth the Sulphur, 
while another part unites with the Silver thus separated 
from the Sulphur, passing through the melted sulphuret, 


10 


OF SULPHERETTED SILVER. 


and carries down with it into the metallic button any 
particle of Gold that remains suspended in the sulphuret¬ 
ted Silver. The crucible is left to cool, and then as the 
separation of the button is not distinctly marked, the 
sixth part of the height of the ingot is struck off, and 
laid aside. 

The Sulphuretted Silver, or upper part of the mass, 
is remelted with fresh Sulphur, and only one thirty- 
second of Litharge. The Sulphuretted Silver obtained 
in the second melting is assayed, and if it contains ever 
so little Gold, it is melted a third time with fresh Sulphur 
and Litharge. The button struck off in these remeltings 
is added to the former. The button of impure Gold 
thus obtained, are melted together, granulated, and again 
worked with Sulphur and Litharge as at first, until, by 
assaying the button, it is found to contain not more than 
five or six parts of alloy, partly Silver and partly Lead, 
to one of Gold, at which time the metal is generally re¬ 
duced to 15 or 20 lbs. The Gold is then refined by 
eupellation, quarting, and parting by Aquafortis, as in 
other cases. 

The masses of Sulphuretted Silver are every six months 
colleeted, and melted in large crucibles with one-fourth 
their weight of Iron, and left to cool. The upper part 
of the mass is Sulphuretted Iron, the lower is composed 
of six-sevenths of Silver, and one-seventh of Lead, which 
are separated by eupellation. The Sulphuretted Iron is 
remelted with one-tenth of Iron, and when completely 
liquid, dusted over with Lithage, which is reduced, and 
the lead falling through the melted mass carries with it 
all small portions of silver. The button thus obtained is 
cupelled separately along with the refuse matters of the 
parting, and yields fine silver. The Sulphuretted Iron, 
that swam over the button, is mixed with -the broken 
crucibles and other refuze matters; as also the impuri¬ 
ties arising in the last mentioned eupellation, namely, 
the Litharge, bead, and scum, are melted, and yield a 
button of lead, which is cupelled, and the Silver reserved 
and added to the next parcel of rare Silver that is to be 
operated upon. The impurities of this eupellation are 


OF separating gold from silver. 11 

laid aside, and added in the smelting of the next parcel 
of the Sulphuretted Iron. 

By this series of operations, there are annually sepa¬ 
rated with some profit four or five pounds of Gold, from 
more than 200,000 cwt. of ore. 

ANOTHER MODE OF SEPARATING A SMALL 
PORTION OF GOLD FROM A LARGE POR¬ 
TION OF SILVER, 

Upon a number of stove holes of afoot in diameter 
there are placed Platina Eggs, each of which contain 
6 lbs. of Granulated Silver, and 12 lbs. Oil of Vitriol. 
All these eggs are covered with a high cap of the same 
metal, with a small opening, a quarter of an inch over, 
at top, to let out the vapours. These stoves are under 
a hood, which opens into the flue, to carry ofi’the vapours. 

As the Sulphuric Acid does not act upon Silver, unless 
heat is applied, a fire is lighted in each of the stoves ; at 
first the solution goes on very fast, and much Sulphurous 
Acid Gas is disengaged, but after two or three hours, 
the solution goes on slower, and it requires 15 hours in 
general to complete the solution 

The vapors exhaled in this dissolution of-Silver, is 
not only Sulphurous Acid Gas, but also Sulphuric Acid 
itself. To avoid being hurtful to the operators, is fitted 
a pipe of Platina or Glass to the hole in the cover of the 
Eggs, which leads into a reservoir, and the Sulphuric 
Acid is condensed. 

The Silver being dissolved, the solution Is poured out 
of the Platina Eggs into stone ware pans, and water is 
added, so as to reduce its density to 15 or 20 degrees of 
Baume’s Hydrometer, or so that a bottle holding a 
pound Avoiniupois of water, shall hold about 18 oz. or 
18 oz. and a half of the solution. The solution is then 
left for some time to settle, and being carefully poured 
off the brown powder; which is in fact the Gold con¬ 
tained in the Silver; slips of Copper are added, and the 
Silver, which is separated by the Copper, carefully 
washed. The Silver obtained is melted in a crucible, 
and run into ingots. 

The brown Gold powder is mixed with a little Salt- 


12 


PROPORTION OF METALS FOR THE CUPEL. 


petre, and melted; the use of the Saltpetre is to sepa¬ 
rate any portion of Copper that may be contained in it. 

The blue solution that is left after the precipitation of 
the Silver being a Sulphurate of Copper, may be evapo¬ 
rated and crystalized, the crystals may bo sold, or pre¬ 
pared in various colors. 

PROPORTION OF LEAD TO COPPER AND SIL¬ 
VER—FOR THE CUPEL. 

Sixteen parts of Lead are quite sufficient to one part 
of Copper, to pass it through the Cupel; and 3-10 of 
Lead presents the most suitable proportion for passing 
one of Silver. The following Table contains the re¬ 
sults of M. D’Areot’s elaborate experiments upon this 
subject. 


ALLOY. 

Lead for 1 

■■MBBHBiaaEB&aiaEUarrJI 

Ratio of the Copper 

Silver. 

Copper. 

of Alloy. 

to the Lead. 

1000 

0 

3-10 

0 


950 

50 

3 

1 

60 

900 

100 

7 

1 

70 

800 

200 

10 

1 

50 

700 

300 

12 

1 

40 

600 

400 

14 

1 

35 

500 

500 

16 or 17 

1 

32 

400 

600 

16 or 17 

1 

26.7 

300 

700 

16 or 17 

1 

22.9 

200 

800 

16 or 17 

1 

20 

100 

900 i 

16 or 17 

1 

17.8 

0 

1000 i 

16 or 17 

1 

16 


Bismuth may be used as a substitute for Lead in cu- 
pellation; two parts of it being nearly equivalent to 
three of Lead. 

Process of Assaying. Weigh in a delicate balance, 
a certian weight of the Metallic Alloy ; a gramme 

















ANOTHER WAY TO ASSAY GOLD. 


13 


(15,444 gr.) in France, and 12 gr. in England. This 
weight is wrapped np in a slip of Lead Foil, or paper, 
should it consist of several fragments. This small par¬ 
cel, thus enveloped, is then laid in a watch-glass, or a 
capsula of Copper, and there is added to it the propor¬ 
tion of Lead suited to the quality of alloy to be assayed ; 
there being less Lead, the finer the Silver is presumed 
to be. If too much Lead be used for the proportion of 
baser metals present, a part of the Silver is wasted: but 
if too little, then the whole of the Copper, &e., is not 
carried oflT, and the button of fine Silver remains more or 
less impure. The Lead must be, in all cases^ entirely 
free from Silver, being such as has been revived from 
pure Litharge; otherwise, errors of the most serious 
kind would be occassoned in the assays. 

ANOTHER WAY TO ASSAY GOLD IN THE HU¬ 
MID WAY. 

After the matter for Assaying has been reduced to 
impalpable powder, it is put into a proper vessel, and 
mixed with two parts of Hydrochloric Acid (Muriatic 
Acid) and set in a sand bath to be boiled for one hour at 
least. After decanting the liquid, and perfectly cooling, 
a new portion of the same acid is poured on the mass, 
and boiled one hour more. 

This treatment with Hydrochloric Acid will take up 
the metal which may be soluble, as Iron, &c. ; and will 
facilitate the subsequent action on the Gold. 

Pour ofl' again the liquid, and wash the residue with 
distilled water,—then pour on it a portion of Aqua- 
regalis, and boil it again for two hours,—in this time, 
all the Gold containing in the mass wdll be dissolved. 
After it has perfectly cooled, decant, and wash the resi¬ 
due with a little distilled water, filter the same through 
paper, and collect these two last fluids together. 

Pour into this solution of Gold, Protosulfate of Iron 
(pure green Vitriol), or the Protochlorure of Pewter. 
The Sulphate of Iron will color the liquid brown, or 
brown-yellow, if there should be only a trace of Gold. 
Should the Gold be in eonsiderable quantity, it will bo 


1'4 


MATERIAL FOR CUPELS. 


thrown down in the shape of a powder. The precipitate 
is thrown on a filter, and the weight of it will indicate 
the quantity of Gold under examination. But it is more 
exact to have melted the precipitate in a suitable cruci¬ 
ble, with addition of borax. The Protochlorure of Pew¬ 
ter, will give the solution of Gold a rose, violet, or pur¬ 
ple color : then the result will be the Precipitate of 
Cassius. This reaction is of a great sensibility, and 
therefore often preferred for Sulphate of Iron. 

Cupels. The best cupels weigh grammes, or 

19.3 gr. The cupels allow the iused oxydes to flow 
through them as through a fine sieve, but are imperme¬ 
able to the particles of metals ; and thus the former 
pass readily down into their substance, while the latter 
remain upon their surface ; the liquid metals presenting 
a hemispherical shape in the cupels, while the fused 
oxyde spreads over, and penetrates the substance like 
water. 

Dimensions of the Muffle or Pot —which is 12 inches 
long ; 6 inches broad inside ; in the clear; inch¬ 
es high inside ; and nearly in the clear. The muffle 
plate is of the same size as the bottom of the muffle. 
The register board being of wood, and divided into 45 
square spaces—upon which the cups are to be placed, 
and also in the same order into the muffle, to avoid con¬ 
fusion in the operation. 

Material for Cupels. The cores of ox-horns, burnt to 
ashes. It depends much upon the selection of the pro¬ 
per material for cupels. The cupels are made in a cir¬ 
cular mould of cast steel, very nicely turned, by which 
they are easily freed from the mould when struck. The 
bone-ash is used, moistened with a quantity of water, 
sufficient to make the particles adhere firmly together. 
The circular mould is filled, and pressed level with its 
surface : after which, a pestle or rammer, having its end 
nicely turned, of a globular or convex shape, and of a 
size equal fo the degree of concavity wished to be made 
in the cupel for the reception of the assay, is placed upon 
the ashes in the mould, and struck with a hammer until 
the cupel is properly formed. It requires a fortnight of 
fine M'eather to dry them sufficiently for use. 


OF DEFSOTTVE ASSAYS. 


An Assay may prove defective for several reasons, 
Sometimes the button or bead sends forth crystalline 
vegetation on its surface with such force, as to make one 
suppose a portion of the Silver may be thrown out of the 
cupel. When the surface of the bead is dull and flat, 
the assay is considered to have been too hot, and it indi¬ 
cates a loss of Silver in fumes. When the tint of the 
bead is not uniform, when its inferior surface is bubly, 
when yellow scales of Oxyde of Lead remains on the 
bottom of the cupel, and the bead adheres strongly to it; 
by these signs it is judged that the assay has been too 
cold, and that the Silver retains some Lead. 

Lastly,, the Assay is thought to be good, if the bead is of 
a round form, if its surface is brilliant, if the lower sur¬ 
face is granular and of a dead white, and if it separates 
readily from the cupel. 

After the Lead is put into the cupel, it gets immedi¬ 
ately covered with a coat of oxyde, which resists the 
admis.sion of the Silver to be assayed, into the melted 
metal; so that the alloy cannot form. When a bit of 
Silver is laid on a lead bath in this predicament, we see 
it swim about for a long time without dissolving. In 
order to avoid this result, the Silver is wrapped up in a 
bit of paper ; and the carbonated hydrogen generated by 
its combustion reduces the film of the lead oxyde, gives 
the bath immediately a bright metallic lustre, and ena¬ 
bles the two metals readily to combine. 

As the heat rises, the Oxyde of Lead flows round 
about over the surface, till it is absorbed by the cupel. 
When the Lead is wasted to a certain degree, a very 
thin film of it remains only on the Silver, which causes 
the iridescent appearance, like the colors of soap-bub¬ 
bles ; a phenomenon, called by the old chemists ful- 
juration. 

When the cupel cools in the process of the assay, the 
oxygenation of the Lead ceases; and, instead of a very 
liquid vitrous oxyde, an imperfectly melted oxyde is 
formed, which the cupel cannot absorb. To correct a 
cold assay, the temperature of the furnace ought to be 
raised, and pieces of paper ought to be put into the 
cupel, till the Oxyde of Lead which adheres to it be re- 


16 


LOSS OF SILVER. 


duced. On keeping up the heat, the assay will resume 
its ordinary train. 

Pure Silver almost always vegetates. Some traces 
of Copper destroys its property, which is obviously due 
to the oxygen which the Silver can absorb, while it is in 
fusion, and which is disengaged the moment it solidifies. 

An excess of Lead, by removing all the Copper at an 
early stage, tends to cause the vegetation. 

The brightening is caused by r,he heat evolved, when 
the button passes from the liquid to the solid state. 
Many other substances present the same phenomenon. 

In the above operation it is necessary to employ Lead 
which is very pure, or at least free from Silver, called 
pure lead. 

It has been observed, at all times, that the Oxyde of 
Lead carries olf with it, into the cupel, a little Silver in 
the state of an oxygen. This effect becomes less, or 
even disappears, when there is some Copper remaining; 
and the more Copper, the less chance there is of any Sil¬ 
ver being lost. The loss of Silver increases, on the other 
hand, with the dose of Lead. Hence the reason why it 
is so important to proportion the Lead with a precision 
which, at the first sight, would appear to be superfluous. 
Hence also the attempts which have, of late years, been 
made to change the whole system of Silver assaying, and 
to have recourse to a method exempt from the above 
causes of error. 

The loss is 1 thousandth for fine Silver. 

4.3 “ for Silver of 900 thousandths; 

4.9 “ for “ of 800 “ 

4.2 “ for “ of 500 “ 

And diminishes, thereafter, progressively, till the alloy 
contains only 100 thousandth of Silver, at which point the 
loss is only 0.4. 

The Chloride of Silver may be reduced without any 
perceptible loss. After having it washed well, immerse 
pieces of Iron or Zinc into it, and add Sulphuric Acid in 
sufficient quantity to keep up a feeble disengagement of 
hydrogen gas. The mass must not be touched. In a 


LOSS OF SILVER. 


few days the Silver is completely saturated. This is 
easily recognised by the color and nature of the product, 
or by treating a small quantity of it with water of amo- 
nia, we shall see whether there be any chloride unre¬ 
duced ; for it will be dissolved by the amonia, and will 
afterwards appear upon saturating the amonia with an 
acid. The chlorine remains associated with the Iron 
and Zinc in a state of solution. The first washings of 
the reduced Silver must be made with an acidulous 
water, to dissolve the oxyde of Iron which may have 
been formed, and the other washings wdth common water. 
After decanting the last washing, we dry the mass, and 
add a little borax to it, in a powdered state. It must 
be now fused. The Silver being in a bulky powder, is 
to be put in successive portions into a crucible as it sinks 
down. The heat should be at first moderate ; but to¬ 
wards the end of the operation it must be pretty strong 
to bring to a complete fusion the Silver and the scoria, 
and to effect their complete separation. In ease it should 
be supposed that the whole of the Silver had not been 
reduced by the Iron and Zinc, a little carbonate of Pot¬ 
ash should be added to the Borax. The Silver may also 
be reduced by exposing the chloride to a strong heat, in 
contact with chalk and charcoal. 

To discover a little mercury in chloride of Silver in the 
humid way, is important. 

It is well known that Chloride of Silver blackens the 
more readily, as it is exposed to an intense light, and 
that even in the diffused light of a room, it becomes soon 
sensibly colored. If it contains four or five thousandths 
of mercury, it does not blacken; it remains of a dull 
white; with three thousandths of mercury, there is no 
marked discoloring in diffused light; with two thou¬ 
sandths, it is slight; with one thousandth, it is much 
more marked, but still it is much less intense than with 
pure chloride. With half a thousandth of mercury, the 
difference of color is not remarkable, and is only per¬ 
ceived in a very moderate light. 

But when the quantity of mercury is so small that it 
cannot be detected by the difference of color in the chlo- 

1 * 


SILVER CONTAINING MERCURY> 


J8 

ride of Silver, it may be rendered quite evident by a very 
simple process of concentration. Dissolve one gramme 
of Silver supposed to contain one-quarter of a thousandth 
of mercury, and let one-quarter of it be precipitate, by 
adding only one-quarter of the common salt necessary to 
precipitate it entirely. In thus operating, the one-quar¬ 
ter thousandth of mercury is concentrated in a quantity 
of Silver four times smaller : it is as if the Silver having 
been entirely precipitated, four times as much mercury, 
equal to two thousandths, had been precipitated with it. 

In taking two grammes of Silver, and precipitating 
only one-quarter by common salt, the precipitate would 
be, with respect to the Chloride of Silver, as if it amount¬ 
ed to four thousandths. By this process, which occupies 
only five minutes, because exact weighing is not neces¬ 
sary, one-tenth of a thousandth of mercury may be de¬ 
tected in Silver. 

It is not useless to observe, that in making these ex¬ 
periments, the most exact manner of introducing small 
quantities of mercury into a solution of Silver, is to 
weigh a minute globule of mercury, and to dissolve it in 
Nitric Acid, diluting the solution so that it may contain 
as many cubic centimetres as the globule weighs of cen¬ 
tigrammes. Each cubic centimetre, taken by means of 
the pipette (or dropping funnel) will contain one milli¬ 
gramme of mercury. 

If the ingot of Silver to be assayed is found to contain 
a greater quantity of mercury—one thousandth for exam¬ 
ple,—the humid process ought cither to be given up in 
this case, or to be compared with cupellation. 

When the Silver contains mercury, the solution from 
which the mixed chlorides are precipitated does not 
readily become clear. 

Silver containing mercury put into a small crucible 
and mixed with lamp-black, to prevent the volatilization 
of the Silver, was heated for three-quarters of an hour in 
a rauiUe, but the Silver increased sensibly in weight. 
This process for separating the mercury, therefore, 
failed. It is to be observed, that Mercury is the only 
metal which has the power of disturbing the analysis by 
the humid way. 


ASSAYING OF GOLD. 


19 


Assaying of Gold. In estimating or expressing the 
fineness of Gold, the whole mass spoken of is supposed to 
weigh 24 carrat each, either real, or merely proportional, 
like the assayer’s weight, and the pure Gold is called 
fine. Thus, if Gold be said to be 23 carrat fine, it is to 
be understood, that in a mass, weighing 24 carrat, the 
■quantity of pure Gold amounts to 23 carrats. 

In such small work as cannot be assayed by scraping 
off a part and cupelling it, it must be ascertained by the 
touch-stone, in comparing the color,—and the result by 
wettnig the two strokes on the stone with aquafortis. 

Six principal circumstances appear to effect the opera¬ 
tion of parting ;—namely, tho quantity of acid used in 
parting, or in the first boiling ; the concentration of this 
acid; the time employed in its application ; the quantity 
of acid made use of in the reprise, or second operation; 
its concentration; and the time during which it is ap¬ 
plied. From experiment it has been shown, that each of 
these unfavorable circum.stances might easily occasion 
a loss of from the half of thirty-second part of a carrat, 
to two thirty-second parts. 44re assayers explain their 
technical language by observing, that the whole mass— 
consisting of twenty-four carrats, this thirty-second part 
denotes 1-768 })art of the mass. It may be conceived, 
therefore, that if the whole circumstances were to exist, 
and be productive of errors, falling the same way, the 
loss would be very considerable. 

It is necessary to follow one uniform-process in the 
assay of Gold. That recommended by the French is as 
follows ; 

Twelve grains of Gold intended to be assayed must be 
mixed with thirty grains of fine Silver, and cupelled with 
108 grains of pure Lead. The cupellation must be care¬ 
fully attended to, and all the imperfect buttons rejected. 
When the cupellation is ended, the button must be re¬ 
duced, by laminating, into a plate of 1^ inch, or rather 
more, in length, and four or five lines in breath. This 
must be rolled up upon a quill, and placed in a matrass, 
capable of holding about three ounces of liquid, when 
filled up to the narrow part. Two ounce” and a half of 
very pure Aquafortis, of the strength oi . 0 degrees ot 


20 


ASSAYING OF GOLD. 


Baurae’s areometer, must then be poured upon it; and 
the matrass beinjT placed upon hot ashes, or sand^ the 
acid must be kept gently boiling for a quarter of an hour; 
the acid must then be cautiously decanted, and an addi¬ 
tional quantity 1 1-2 ounces must be poured upon the 
metal, and slightly boiled for twelve minutes. This be¬ 
ing likewise carefully decanted, the small spiral piece of 
metal must be washed with filtered river water, or dis¬ 
tilled water, by filling the matrass with this fluid. The 
vessel is then to be reversed, by applying the extremity 
of its neck against the bottom of a crucible of fine earth, 
the internal surface of which is very smooth. The an¬ 
nealing must now be made, after having separated the 
portion of water which has fallen into the crucible ; and, 
lastly, the annealed gold must be weighed. For the 
certainty of this operation, two assays must be made in 
the same manner, together with a third assay upon Gold 
of 24 carrat, or upon Gold the fineness of which is per¬ 
fectly and generally known. 

The phenomena of the cupellaticn of Gold are the same 
as of Silver, only the operation is less delicate, for no 
Gold is lost by evaporation or penetration into the bone- 
ashes, and therefore it bears savely the highest heat of the 
assay furnace. The button of Gold never vegetates, and 
need not, therefore, be drawn out to the front of the muflle, 
but may be left at the further end, till the assay is comple¬ 
ted. Copper is retained more strongly by Gold than it is 
by Silver; so that with it, J6 parts of Lead are required 
to sweat out 1 of Copper ; or, in general, twice as much 
Lead must be taken for the Copper alloys of Gold, as for 
those of Silver. When the Copper is alloyed with very- 
small quantities of Gold, cupellation would afford very 
uncertain results ; we must have then recourse to liquid 
analysis. 

M. Vanquelin recommends to boil 60 parts of nitric 
acid at 22® Baume, on the spiral slips or cornet of Gold 
and Silver alloy, for twenty-five minutes, and replace the 
liquid afterwards by acid of 32®, which must be boiled on 
it for eight minutes. This process is free from uncertainty 
when the assay is performed upon an alloy containing a 
considerable quantity of Copper. But this is not the case 


ASSAYING OF GOLD. 


in assaying finer Gold ; for then a little Silver always re¬ 
mains in the Gold. The surcharge which occurs here is 
two or three thousandths; this is too much, and it is an 
intolerable error when it becomes greater, which often 
happens. This evil may be completely avoided by em¬ 
ploying the following process of M. Chatidet: 

He takes 0,500 of the fine Gold to be assayed ; cupels 
:it with 1,500 of Silver, and 1,000 of Lead; forms, with 
the button from the cupel, a riband or strip three inches 
long, which he rolls into a cornet. He puts this into a 
matrass with acid, at 22® B., which he boils for three or 
four minutes. He replaces this by acid of 32® B,, and 
boils for ten minutes ; then decants off, and boils again 
with acid of 32®, which must be finally boiled from eight 
to ten minutes. 

Gold thus treated is very pure. He washes the cor¬ 
net, and puts it entire into a small crucible permeable to 
water; heats the crucible to dull redness under the 
mufflp, when the Gold assumes the metallic lustre, and 
the cornet becomes .solid, J,t is now taken out of the 
crucible and weighed. 

When the .alloy contains platina,^ the assay presents 
greater difficulty. In general, to separate the Platina 
from the Gold with accuracy, we must avail ourselves 
of a peculiar property of Platina : when alloyed with Sil¬ 
ver it becomes soluble in nitric acid. Therefore, by a 
proper quartation of the alloy by cupellation, and boiling 
the button with nitric acid, we may get a residue of 
pure Gold. If we were to treat the button with sul¬ 
phuric acid, however, we should dissolve notldng but the 
Silver. The Copper is easily removed by cupellation. 
Hence, supposing that we have a quaternary compound 
qf Copper, Silver, Gold and Silver, and Gold, we first 
cupel it, and weigh the button obtained ; the loss denotes 
the Copper. This button, treated by sulphuric acid will 
suffer a loss of weight equal to the amount of Silver pre¬ 
sent. The residue, by quartation with Silver, and boiled 
with nitric acid, will part with its platina, and the Gold 
will remain pure, 


22 


manufactiTrii^g of copper,- 


COPPER. 

Manufacturing and Assays of Copper. The first thing 
is to make a sample that will represent the whole mass 
to be valued ; with which view, fragments must be taken 
from different spots, mixed, weighed, and ground to¬ 
gether. A portion of this mixture being tried by the 
blow-pipe, will show, by the garble or sulphurous smelf 
of its fumes, whether arsenic, sulphur, or both, be the 
mineralizers. In the latter case, which often occurs, 
100 grains or 1000 grains of the ore are to be mixed with 
one half its weight of saw-dust, then imbued with oil, 
and heated moderately in a crucible till all the arsenical 
fumes be dissipated. The residue, being cooled and 
triturated, is to be exposed in a shallow earthen cup, to 
a roasting heat, till the sulphur and charcoal be burned 
away. What remains, being ground with half its weight 
of calcined borax, one-twelfth its weight of lamp-black, 
next made into a dough with a few drops of oil, is to be 
pressed dow'ii into a crucible, which is to be covered 
with a luted lid, and to be subjected, in a powerful air 
furnace, first to a dull red heat, and then to vivid ignition 
for twenty minutes. On cooling and breaking the cruci¬ 
ble, a button of metallic Copper will be obtained. Its 
color and malleability indicate pretty well the quality, as 
does its weight the relative value of the ore. It should 
be cupelled with Lead, to ascertain if it contains Silver 
or Gold. 

I f the blow-pipe trial showed no Arsenic, the first 
calcination may be omitted ; and if neither Sulphur or 
Arsenic, a portion of the ground ore should be dried, and 
treated directly with borax, lamp-black, and oil. It is 
very common to make a dry assay of Copper ores, by 
one* roasting and one fusion along with three parts of 
black-flux. From the weight of the Metallic button the 
richness of the ore is inferred. 

The Humid Assay is more exact, but it requires more 
skill and time. 

The Sulphur and the Silver are easily got rid of by the 
acids which do not dissolve them, but only the metallic 
oxydes and other earths. These oxydes may then be 


ASSAY OF COPPER ORES. 


23 


thrown down by their appropriate reagents, the Copper 
being precipitated in the state of either the black oxyd© 
or pure metal. One hundred and five parts of black 
oxyde represent one hundred of Copper. Before enter¬ 
ing upon the complete analj'sis of an ore, preliminary 
trials should be made, to ascertain what are its chief 
constituents. I fit be Sulphuret of Copper, or pyrites, 
without Silver or Lead, 100 gr. exactly of its average 
powder may be weighed out, treated in a matrass with 
Doiling Muriatic Acid for some time, gradually adding a 
few drops of Nitric Acid, till all action ceases, or till 
the ore be all dissolved. The insoluble matter found 
floating in the liquid contains most of the Sulphur; it 
may be separated upon a filter, washed, dried, and 
weiged ; then verified by borning away. The incom¬ 
bustible residue, treated by Muriatic Acid may leave an 
insoluble deposit, which is to be added to the former. To 
the whole of the filtered solutions Carbonate of Potash 
is to be added : and the resulting precipitate, being wash¬ 
ed, and digested repeatedly in water of Ammonia, all its 
cupric oxyde will have been dissolved, whenever the 
Ammonia is no longer rendered blue. 

Coustic Potash boiled with the amoniacal solution, 
will separate the Copper in the state of black oxyde; 
which is to be thrown upon the filter, washed, dryed, 
and weighed. The matter left undissolved by the Am¬ 
monia, consists of oxide of Iron, with probably a little 
Alumina. The latter being separated by Coustic Potash, 
the Iron oxyde may be also washed, dried, and weighed. 
The powder which originally resisted the Muriatic Acid 
is Silver. 

ASSAY OF COPPER ORES, WHICH CONTAIN 
IRON, SULPPIUR, SILVER, LEAD AND ANTI¬ 
MONY. 

One hundred grains of ores, previously sampled and 
pulverized, are to be boiled Math Nitric Acid, adding fresh 
portions to it from time to time, till no more of the mat¬ 
ter be dissolved. The whole liquors which have been 
successively digested and decanted off are to be filtered 


134 


Native arseniAtes of copper. 


and treated with common salt, to precipitate the Silver 
in the state of a chloride. 

The Nitric Acid by its'reaction on the Sulphur, having 
generally Sulphuric Acid, this will combine with the 
Lead oxyde at the same time constituting insoluble Sul¬ 
phate of Lead, which will remain mixed with the 
gangue. Should a little of Nitrate of Lead remain in 
the liquid, it may be thrown down by Sulphurate of 
Soda, after the Silver has been separated. The dilated 
liquid, being concentrated by evaporation, is to be 
mixed with Ammonia in such excess as to dissolve the 
cupric oxyde, while it throws down all the oxyde of 
Iron and Alumina; which two may be separated, as 
usually, by a little Coustic Potash. The portion of ore 
insoluble in tlie Nitric Acid beinjr digested in Muriatic 
Acid, everything will be dissolved except the Sulphur 
and Silex. These being collected upon a filter, and 
dried, the Sulphur may be burned away, whereby the 
proportion of each is determined. 

Ores of the Oxyde of Copper are easily Analyzed by 
solution in Nitric Acid, the addition of Ammonia, to 
separate the other metals, and precipitation by Potash. 
The Aatitic Cur6o«atc is analyzed by calcining 100 gr. 
when the loss of weight will show the amount of water 
and Carbonic Acid, then that of the latter may be found, 
by expelling it from another 100 gr., by digestion in a 
given weight of Sulphuric Acid. The Copper is final¬ 
ly obtained in a metallic state by plunging bars of Zinc 
into the solution of the Sulphate, 

The Native Arseniates of Copper are analyzed by dry- 
ing them first at a moderate heat; after which they are 
to be dissolved in Nitric Acid. To this solution one of 
Nitrate of Lead is to be added, as long as it occasions a 
precipitate; the deposite is to be drained upon a filter, 
and the clear liquid which passes through, being evapo¬ 
rated nearly to diyness, is to be digested in hot Alcohol, 
which will dissolve everything except a little Arseniate 
of Lead, This being added to the Arseniate first ob¬ 
tained, from the weight of the whole, the Arseniac Acid, 
constituting 25 per cent., is directly inferred. The Al¬ 
coholic solution being now evaporated to dryness, the 


TREATMENT OF GOLD. 


2a 


residue is to be dij^ested in water of Ammonia, when the 
Cupric oxyde will be dissolved, and the oxyde of Iron 
will remain. The Copper is procured in the state of 
black oxyde, by boilinjr the filtered Ammoniacal solution 
with the proper quantity of Potash. 

The Analysis of Muriate of Copper — Atacamite —is an 
easy process. The ore being dissolved in Nitric Acid, 
a solution of Nitrate Silver is added, and from the weight 
of the Chloride precipitated, the equivalent amount of 
Muriate or Chloride of Copper is given ; for 100 of Chlo¬ 
ride of Silver represents 93 of Chloride of Copper, and 
43.8 of its metallic basis. This calculation may be veri¬ 
fied by precipitating the Copper of the Muriate from its 
solution in diluted Sulphuric Acid, by plates of Zinc. 

The Phosphate of Copper may be analyzed cither by 
solution in Nitric Acid, and precipitated by Potash; or 
by precipitating the Phosphoric Acid present, by means 
of Aretate of Lead. The Phosphate of Lead thus ob¬ 
tained, after being washed, is to be decomposed by diliile 
Sulphuric Acid. The insoluble Sulphate of Lead, being 
washed, dryed, and weighed, indicates by its equivalent 
the proportion of Phosphate of Lead, as also of Phosphate 
of Copper ; for 100 of Sulphate of Lead correspond to 
92.25 Phosphate of Lead, and 89.5 Phosphate of Coj)- 
per ; and this to 52.7 of the black oxyde. 

METALLUPvGIC TREATMENT OF GOLD. 

The Gold found in the sands of rivci’s, or auriferous 
soils, needs not to be subjected to any metallurgic pro¬ 
cess, properly speaking. By washing, it is separated Ifom 
the sands, upon inclined tables, sometimes covered with 
cloth, and then by hand in wooden bowls of a particular 
form. Amalgamation is employed to carry oil'from the 
sand the minuter particles of Gold they may contain. 
Also a plank with twenty-four transverse grooves cut in 
its surface. The plank is kept in an inclined position, 
and the sand to be washed is put on in the first grove, 
water is then thrown on it, when the Gold mixed with a 
little sand collects usually towards the lowest furrow. 
The mixture is then removed into a flat wooden basin, 

2 


TKEATMENT OF 0OI.J>. 




find by a poo'uliar motion of the handf<, separated the Gold 
(’ntii’cly I'roin the sand. Tlio richest of Ihe auriferious 
ores consist of the native Gold quite visible, disseminated 
ill a ^angiio, but the veins are seldom continuous for any 
leno'fh. 

The other ores are, Auriferious IMctaDic Sulphurets, 
Mieh as Hulphurets of Copper, Silver, Arsenic, &c., and 
oiirticularly. 

'J’he stony ores are first ground in the stamping mill, 
enil then washed in hand basins, or on vrooden tables. 

The Auriferious Sulp!)urcls are much more common, 
but much j)onrer than the lormer ores; some eontain 
only one 200,00()th of (fold, and yet they may be worked 
with advantage, when trcatc ' with skill and economy. 

'J'he Gold of these ores ar< separated by two diUcrent 
proee.'^^ges, namely, by fusion end anmlgamation. 

'J'he Auriferious Metallic Snlphnrets are first roasted, 
thiUi melted into mattes, whieli are roasted again ; nest 
fused with Tmad, wiienco an Auriferious Lead is obtained, 
svddeli maybe refined by the process of c-upellation. 

AVlien tljo Gold ores nro very rich, they are melted di- 
jcf'ily with Lead, without prpliminary calcination or 
fusion. Tliese processes are, hov,'ever,"]ittio practiced, 
because tiiey art* less economical nnd certain than amal- 
gnmatlc'n, es])eeially when the Gold ores are very ]>oor. 

If these ores consist of Cojqier pyrites, and it' their 
treat-ment has been pushed to the point of obtaining Au- 
rderious rose Copper, or even black Copper including 
Gold, the precious metal cannot be separated by the 
(U'oec'ss of liquation, because the Gold having more 
oninify for Copper than for Lead, can be but partially 
riin ojf by the Lead. 3^’or these reasons the process of 
(uialvsation i.s far preferable. 


Tf 


10 

ii! whio 
mimttcf 


iroeefis being the same for f^ilvcr. The rich ore? 


i_1he native Gold is apparant, and merely discri- 
lin a strong gang, arc directly triturated with 
(Aiick.silver Nvitliout any jireparatory operation. As to the 
poor ores, withwhicdi the Gold seems lost amid a great 
mass of Iron, tSulphuret -of Copper, &o., they are sub¬ 
jected to a roasting before being amalgamated. This 
proces.s seems rccpiisite to lay hare the Gold enveloped 



TIIEATMENT OF OOLD. 


27 


in the Sulphurots. Tho Quicksilver with which the ores 
arc now ground, sizes tho whole of the Gold, in however 
small quantities the metal may bo present. 

The Gold procured by the reftnijig process with Lead, 
is Iree from Copper and Lead, but it may contain Iron, 
Tin, or Silver. It cannot be separated from Iron and 
Tin without great difficulty and expense, if tho propor¬ 
tion of Gold be too small to admit of tho employment of 
Muriatic Acid. 

By cupellation with Lead, Gold may be deprived of 
any Antiraoniy unitecl with it. 

Tin gives Gold a remarkable hardness and brittleness; 
a piece of Gold ( posed for some time over a bath of 
red hot Tin, bocom. ; brittle. Tho same happens more 
readily over Antinii ay, from tho volatility of this metal, 
a 2,000 part of Antimony, Bismuth, or Lead, destroys 
the ductility of Gold, L he Tin may be got rid of by 
throwing some Corrosive Sublimate or Nitre into a cru¬ 
cible containing the melted alloy. By tho first agent, 
perchloride of Tin is volatilized, by the second, Stannate 
of Potash forms, which is carried olT in the resulting 
alkaline scoria. 

If the Gold do not contain two-thirds of its weight in 
Silver, this metal, being thoroughly enveloped by the 
Gold, is partially screaned from the action of the Acid, 
Whenever, therefore, it is known by trial on a small 
scale, that the Silver is much below tho proportion, wo 
must bring tho alloy of Gold and Silver to that standard 
by adding a requisite quantity of the latter metal. The 
procees is called quartation. 

The alloy is then granulated or laminated ; ancl twice 
to thrice its weight of Sulphuric or Nitric Acid is to bo 
boiled upon it; and when it is judged the solution has 
been pushed as far as possible by tho first acid, it is de¬ 
canted, and new acid is poured on. Lastly, after having 
washed the Gold, some Sulphuric Acid is to bo boiled 
over it, yiiiich carries off a two or three thousandth part 
of Silver, which Nitric Acid alone could not dissolve. 
Thus perfectlv pure Gold is obtained. 

The Silver held in solution by Sulphuric or Nitric Acid 


DIFFERENT KINDS OF SILVER. 


is precipitated in the metallic state by Copper, or in the 
state of chloride, by sea-salt, 

SILVER OCCURS UNDER MANY FORMS IN 

NATURE, 

1. Native Silver is distinguished chemically from Gold 
and Gold and Silver by its ready solubility in Nitric Acid, 
and frond almost all other metals, by its saline solution 
alfording a curdy precipitate with a most minute quanti¬ 
ty of sea-salt, or any soluble chloride. Native Silver on 
account of its being more or less alloyed with other 
metals, it differs a little in malleabilitv, lustre, densitv^ 
&c. It sometimes occurs crystallized in wedge-lbrm, 
octahedrons, in cubes, and cube-octahedrons. At other 
limes it is found in dendritic shapes, or arboreseences, 
resulting from minute elirystals implanted upon each 
other. But more usually it presents itself in small 
grains without determinable form, or in amorphous 
masses of various magnitude. The Gangues (mineral 
matrices) of Native Silver are so numerous, that it may 
be said to occur in all kinds of rocks. At one time it 
appears as if liltered into their fissures, at another as 
having vegetated on their surlacc, and at a third, as if 
impasted in their substance. Such varieties arc met 
with principall}^ in the mines of Peru. 

The native metal is found in almost all the Silver mines 
now worked ; but especially in that of Kongsbery in 
Norway, in carbonate and Iluate of lime, &c., at Schlan- 
genberg, in Siberia, in a Sulphate of Barytes; at Alli- 
mont, in a ferruginous clay, &c. Large masses of Native 
Silver have been discovered in various localities. 

The metals most usually associated with Silver in the 
Native Alloy, are Gold, Copper, Arsenic, and Iron. At 
Andreasbery and Guadalcanal it is alloyed with about'livo 
per cent, of Arsenic. The auriferious native Silver is 
the rarest; it has a Brass-yellow color. 

2. Jlntimonial Silver. This rare ore is yellowish- 
blue; destitute of malleability; ever very briule; spec, 
grav. 9.5. It melts before the blow-pipe, and affords 
white fumes of Oxyde of Antimony; being readily dis- 


different kinds of silver. 


29 


tinguished from Arseniacal Iron, and Arseniacal Cabatt, 
by its lamellar fracture. It consists of 76 to 84 of Silver, 
and Iroin 24 to 16 of Antimony. 

3. Mixed Antimonial Silver. At the blow-pipe it emits 
a strong garlic smell. Its constituents are, Silver 16, Iron 
41, Arsenic 35, Antimony 4. It occurs at Andreasberg. 

4. Sulphuret of Silver. This is an opaque substance, 
of a dark-gray or leaden hue ; sligntly malleable, and 
easily^ cut with a knife, when it betrays a metallic lustre, 
1 he Silver is easily separated by the blow-pipe. It con* 
sists ot 13 of Sulphur to 89 of Silver, by experiment; 
13 to 87 are the theoretic proportions. Its spec. grav. 
is 6.9. It occurs crystallized in most Silver mines, but 
©.specially in those of Freybery, Joachimsthal in Bohe¬ 
mia, Schemnitzen, in Hungary, and Mexico. 

5. Red Sulphuret of Silver., Silver Glance. Its spec, 
grav. is 5.7, It contains from 84 to 86 of Silver. 

6. Sulphuretted Silver, with Bismteth. Its constituents 
are, Lead 35, Bismuth 27, Silver 15, Sulphur 16, with 
a little Copper and Iron, It is rare. 

7. Antimoniated Sulphuret of Silver. The red Silver 
of many mineralogists, is an ore remarkable for its lustre, 
color, aud the variety of its forms. It is friable, easily 
scraped by a knife, and affords a powder of a lively crim¬ 
son red. Its color in mass is brilliant red, dark red, or even 
metallic reddish-blaek. It crystallizes in a variety of 
forms. Its constituents are, Silver from 56 to 62 ; Anti¬ 
mony from 16 to 20 ; Sulphur from 11 to 14; and Oxygen 
from 8 to 10. The Antimony being in the state of the 
Purple Oxyde in this ore, is reckoned to be its coloring 
principle. It is found in almost all Silver mines ; but 
principally in those of Freybery, Sainte-Marie-aux- 
Mines, and Gaudalvanal. 

8. Black Sulphuret of Silver, is blackish, brittle, cel¬ 
lular, affordirg globules of Silver at the blow-pipe. It 
is found only in certain mines, at Allemont, Freyberg; 
more abundrntly in the mines of Peru and Mexico. The 
Spaniards coll it Negrillo. 

9. Chloride of Silver, or Horn Silver. In consequence 
of its semi-ti ansparent aspect, its yellowish or greenish 
color, and such softness that it may be cut with the nail, 


30 


EXTRACTION OF SILVER FROM ITS ORES, 


this ore has been compared to horn, and may be easily 
recognised. It melts at the llame of a candle, and may 
be reduced when heated along with Iron or black*llux, 
which are distinctive characters. It is seldom chry.stal- 
iized, but occurs chiefly in irregular forms 5 sometimes 
covering the Native Silver as with a thick crust; as in 
Peru and Mexico. Its density is only 4.74. 

Chloride of Silver sometimes contains GO or 70 per 
cent, of clay; and is then called Butter-milk ore, by the 
German miners. The blow-pipe causes globules of 
Silver to sweat out of it. This ore is rather rare. It 
occurs in the mines of Potosi, of Annaberff. Trcvbcro-, 
Allemont, Schlangenberg in Siberia. &c, 

• 10. Carbonate of Silver. A species little known, has 
been found hitherto only in the mine of S. Wcneeslas, 
near Walbach. 

EXTRACTICN OF SILVER FROM ITS ORES, 

The Spanish mode is to grind the ore and tnix it nj) 
with water into a paste. When this is half dry, it is 
mixed with salt and then roasted. Afterwards Quick¬ 
silver is added, heated along with the ore, the whole 
ground together, and at last washed in a stream of water, 
to carry off the saline and earthy particles. 

When the water goes clear, the amalgam is .squeezed 
in bags, to get rid of the superfluous IMcrcury, moulded 
in wooden moulds jierforated at bottom like a calendar ; 
the masses thus produced laid upon a Copper-plate, full 
of holes, over a Trevet, under which is a large vc.ssel of 
water. The whole is then covered with a bell of earthen¬ 
ware, which is surrounded with fire, by which the Mer¬ 
cury is distilled into the water, and the Silver left upon 
the Copper-plate. Some ores arc roasted before the salt 
is added. 

Silver is also obtained in Saxony, by means of Mer¬ 
cury, in an amalgamation work, The ores used in said 
works, are partly ores in which Native Silver is dissemi¬ 
nated in a matrix without pyrites, and partly of pj^ritous 
ores containing Silver. The first are stamped and washed 
before they are delivered iiq and the others are only 
dressed and washed in basket sieves. 


EXTKACTION OP SII.VEn FROM 1T3 ORES. IM 

The ores are assayed, and mixed so that the mixed 
ore may contain 3 1-3 or 4 ounces of Silver in a cwt, : 
but as in this proportion there is only 1 or ounce <4' 
Native Silver, which is the only part that can be acted 
upon by the Merctiry, the mixture is so mana^'ed that 
each cwt. of ore at the same time that it contains 3 1-3 
or 4 ounces of Silver, may also contain 37 pounds (»i 
Sulphuretted Metal, or about 30 of Sulphur. 

l\) the mixed ores are added, 1-10 its weight of com¬ 
mon salt, and they are then roasted in a revcrlicratoi'V 
furnace ; the roasted mass, which of course contain.^ Sul¬ 
phate of Soda and Muriate of Silver, mixed with tin* 
Native Silver, is screened, to separate those parts tha; 
have run together again, and these being brokensmall and 
mixed.with 1-50 or 1-30 their weight of .salt, arc roasted 
afresh. 

The roasted ore that passes the first sccrcn is again 
screened and divideded into three finenesses ; the two 
finest parcels are ground into a fine powder, the coarsc.st 
is mixed with the ore that has run together, treated in the 
same manner; and thus the whole of the ore is at last 
reduced to a uniform powder. 

Ten cwt. of the ground ore are then put into cacdi 
of the amalgamation barrrels; three cwt, of pure water 
being previously put in each, 

The barrels thus charged having been turned for 3 
hours to mix the ore with the water, there are added to 
each 5 cwt, of Mercury, and GO pounds of Iron forged 
ill circular plate.s. 

The barrels making 18 or 30 turns in a minute, and arc 
turned for 18 hours ; when they are thrown sueccssivoly 
out of gear, and the bung-hole being opened, a wooilon 
pipe is inserted in it, with a short length of leather liosc, 
closed at the end by a.screw'-cock. The barrel thus fit¬ 
ted, is turned half round by the hand, and the hose being 
placed in the gutter, the cock is opened, and the Mer¬ 
cury run into a filter of tickeii, tiirough wiiich tlc’ 
liipiid Mercury runs into a ci.stern, to bo used over again : 
and the amalgam remains on the filter. 

The barrel being again turned, with its bang-hole uji- 
permo.st, is filled with water, and stopped, then thrown 


32 


SILVER REFINED BY CHARCOAL. 


into gear to mix the whole, and after emptied in a similar 
manner of its contents, into gutters that convey them to 
the washing house. 

The amalgam that remains on the ticken filters, is 
composed of six parts of Mercury and one of Silver, and 
is distilled to separate the two metals. 

SILVER REFINED BY CHARCOAL. 

A layer of three inches of small pieces of charcoal is 
Icept at the bottom of a crucible by a false bottom ; sixty 
jiounds of Silver in ingots are melted in this crucible, and 
kept in fusion for seven or eight hours. The vapors 
from the charcoal causes it to boil as violently as water 
on a quick fire, although silver alone, melted in an equal 
degree of heat, had only a slight motion on its surface. 
This mode of refining furnishes very pure Silver, perfect¬ 
ly free from Lead; the process is evidently analogous 
to the poling of Copper and Iron. 

Solder for Silver. This is made by melting three parts 
of Silver with seven of Copper, or four of Silver with six 
of Copper. 

Silver Gilt Plate. Silver is gilded in the same man- 
iic” as Copper, but with an amalgam of Gold. 

Nitric Solution of Silver. This is prepared by dis¬ 
solving granulated Silver in Nitric Acid, sp.gr. 1.500 
diluted with an equal weight of water, until no more 
Silver is taken up. 

It is used to prepare the Lunar Caustic of the Sur¬ 
geons, and to ascertain the presence of Muriatic Acid in 
mineral waters. 

The Lunar Caustic. This Salt is obtained by evapo¬ 
rating gently the Nitric solution of Silver to dryness, in 
a Silver vessel, continuing the heat until it melts, and 
when in quiet fusion, pouring it into moulds, to cast it 
into sticks, the size of the barrel of a common quill. 

Sulphate of Silver. This sulphate is best made by 
addin" Sub-Carbonate of Soda to a Nitric solution of 

C3 

Silver, to throw down the Carbonate of Silver, and then 
dissolve this carbonate in weak Sulphuric Acid. It is 
used to ascertain the presence of Muriatic Acid in mine¬ 
ral waters. 


SKPAKATma SILVER FROM LEAD. S3 

Acetate of Silver, is formed by dissolving in hot Acetic 
Acid, the Carbonate of Silver, which is precipitated 
when Sub-Carbonate of Soda is added to the Nitric So¬ 
lution of Silver. It is also used to ascertain the presence 
of Muriatic Acid in mineral waters. 

To Reduce Chloride of Silver by Colophony. (Black 
Bosin.) Mix the Chloride of Silver with one-third of 
its weight of Colophonia, and heat the mixture mode¬ 
rately in a crucible till the flame ceases to have a green¬ 
ish-blue color ; then suddenly increase the fire, so as to 
melt the metal into an injjot. 

Solution of the Hyposulphite of Potash, Soda, and Lime, 
which are bitter salts, dissolve Chloride of Silver, a taste¬ 
less substance, into liquids possessing the most palling 
sweetness, but not at all of any metallic taste. 

Iodine of Silver is remarkable for changing its color 
alternately with heat and cold. If a sheet of wdiite paper 
be washed over with a solution of Nitrate of Silver, and 
afterwards with a somewhat solution of Hydrodrate of 
Potash, it will immediately assume the pale yellow’ tint of 
the cold Silver I odine. On placing the paper before tho 
fire, it wflll change color from a pale primrose to a gaudy 
brilliant yellow, like the Sun-flow’er; and on being cooled 
it wdll again resume the primrose hue. These altera¬ 
tions may be repealed infinitely, provided the heat be 
not too great. 

Separating Silver from Lead. Since lately, the only 
operations employed for separating Silver from Lead in 
England w^ere the following :— 

1 . Cupellation, in which the Lead w^as converted into 
a Vitrous Oxyde, w'hich was floated off from the surface 
of the Silver. 

2. Reduction of that Oxyde, commonly called Litharge. 

3. Smelting the bottoms of the Cupels, to extract tho 
Lead which had soaked into them, in a glassy state. 

Cupellation and its too complimentary operations were, 
in many respects, objectionable pro.cesses, from the inju¬ 
rious effects of the lead vapour upon the workmen,, lastly 
the very considerable loss of metallic Lead, amounting 
to seven per cent at least from the immense consump¬ 
tion of fuel. Hence, unless the Lead were considerably 


34 


EXTHACTING SILVER EROJI VOOIl ALLOY. 


rich in. Silver, it would not bear the expense of cupella- 
tioii. 

Recently, a new method to extract Silver from very 
poor alloy, which, otherwise, could not be worked to 
any advantage, is practised in Northumberland (Eng¬ 
land.) The process is founded upon the following phe¬ 
nomena : 

After melting completely an alloy of Lead and Silver, 
if it cools very slowly, by constantly stirring with a rake, 
at a certain period, a continually increase of numerous 
imperfect little crystals will appear, which may be taken 
out with a drainer, exactly as crystals of sea-salt arc re - 
moved deposited during the concentration of brine, or 
those of sulphate of Soda, as its agitated solution cools. 
On submitting to analysis, the metallio crystals thus sep¬ 
arated, and also the liquid metal deprived of them, it v/ill 
be found, the former to be lead almost alone,—but the 
latter to be rich in Silver, when compared with the origi¬ 
nal alloy. The more the cry.stalline particles, as drained 
Irom the metallic bath, the richer does the mother liquid 
become in Silver. In practice, the poor lead is raised by 
this means to the standard of the ordinary Lead of 
litharge works. This very valuable alloy is then sub¬ 
mitted to cupellation; by this process, only eight-tenths 
of a per cent, is the loss, instead of seven. These ninc- 
tenths of the Lead separated by the drainer, are imme¬ 
diately sent into the market without other loss than the 
trifling one of about half of a cent, involved in reviving a 
little dross trimmed off the surface of the melted metal 
at the beginning of the operation. 

The smelting house for this purpose is extremely sim¬ 
ple. It contains three hemispherical cast iron pans, 41 
inches in diameter, and one-quarter of an inch thick. 
The three pans are built in one straight line, the broail 
flange at their edge being supported upon brick work. 
Each pan has a dischai'ge pipe proceeding laterally from 
one side of its bottom, by which the melted metal may be 
run out when a plug is withdrawn,—and each is heated 
by a small separate fire. 

Three tons of the argentiferous Lead constitutes one 
charge of each pan 5 and so soon as it is melted, the fire 


SILVER REDUCEB FROM MBRIaTE OF GOLD. 

i.s withdraMm ; the flite, pfrate-doof, and ash-pit are im¬ 
mediately closed, and made air-ti^ht with brick and clav* 
lute. I he apitation is now commenced, with a round 
bar of iron, terminatinir with a chisel-point, the workman 
beinsf instructed merely to keepmovinij that simple rake 
constantly in the pan, but more especially towards the 
edges,-—where the solidification is apt to begin. He 
must be carclul to take out the crystals, progressively as 
they appear, with an iron drainer, heated a little higher 
than the temperature of the melted bath. The liquid 
metal in the drainer, flows readily back tli/ongh its per¬ 
forations, and may be at any rate efTectually detached 
by giving the ladle two or three jogs The solid portion 
remains in the form of a spongy, semi-crystalized, semi¬ 
pasty mass. 

The proportion of crystals separated at each melting, 
depends upon the original quality of the alloy. If it be 
poor, it is usually divided in the proportion of twm-thirds 
of poor crystals, and one-third of rich liquid metal; but 
this proportion is reversed if the alloy contains a good 
deal of Silver. 

The separation of the crystals from the mother metal, 
may, from a great body of poor crystals, be also parted 
by opening the discharge-pipc, and running off the liquid, 
while the workman keeps stirring, to facilitate the sepa¬ 
ration of the two. 

SILVER REDUCED FROM MURIATE OF SILVER 

In many operations of Chemistry, the Muriate, Chlo- 
rure. or Chln;-ide of Silver, formerly called corned, or 
horn Silver, is formed. 

To obtain the Silver, the common method is to moisten 
the Muriate of Silver and form it into a ball; some pearl- 
ash is then put at the bottom of a crucible, the ball laid 
upon it, and covered with more pearinsh : the whole is 
then exposed to a gradual heat, until the Silver is re¬ 
duced and melted. 

The Muriate of Silver may be still better iqixed with 
one-fifth its weight of dry quick lime, and one-twentieth 
of charcoal in powder, and heated till the Silver is re¬ 
duced. 


56 


ASSAYING OF SILVER ORES. 


The Silver may also be obtained by covering^ it with a 
small quantity of water soured with Sulphuric Acid^ or 
Muriatic Acid, and putting into the water a bright piece 
of Iron, or of Zinc. 

ASSAYING OF SILVER ORES. 

The value of Silver, and the small quantity in which 
it is often found in its ores, require those ores to be as¬ 
sayed with great care. The ores of Silver are, for this 
purpose, divided into three kinds :—1. Ores of easy fu¬ 
sion., under which are comprised native Silver ;—the 
vitreous and corneous Silver ores;—the red and white 
Silver ores,—and some others. 2d. Wash Ores, which 
are mixed with stony matter, and must be separated 
from it by washing. 3d. Refractory Ores, which are 
either mixed with refractory materials, or with other 
kinds of ores, as cobalt, pyrites, or copper, in such a 
manner that they cannot be separated from them by 
washing. 

With respect to the Silver ores of easy fusion, there 
are three operations chiefly to be attended to :—Roast¬ 
ing, scorification with Lead,—and cupellation. As to 
roasting, there are, it is true, some Silver ores that may 
be assa 3 "ed without roasting, which are suffered to roast 
during the scorification by Lead. It is, however, safer 
previously to roast the ore a little, particularly if it 
should contain a small quantity of Sulphur or Arsenic. 

The scorification with Lead is performed in the fol¬ 
lowing manner: One assay cwt. of ore is to be taken, 
either before or after roasting, and eight cwt. of granu¬ 
lated pure lead added to it. First, one half of the Lead 
is to be put into the clay test, or capsule, and upon this 
the ore, which is afterwards to be covered with the re¬ 
mainder of the Lead. Immediately upon this, the cap¬ 
sule is to be put into a well-heated assaying furnace ;— 
at first, at the mouth of the muffle only, but at length 
quite into it, and a red hot coal is placed before the 
mouth of the furnace. 

When tlie lead begins to melt, and the ore swims upon 
its surface, the mouth of the furnace is to be opened, the 
coal removed, and the capsule drawn more forward, that 


ASSAYING OF SILVER ORES. 


37 


the Sulphur and Arsenic may be better dissipated and 
expelled from the ore. After this, the test or capsule 
is again put into the furnace, a red hot coal once more 
placed before the mouth of the latter, which is then shut 
up till the Lead is seen quite bright and shining in the 
middle of the capsule, and the ore flowing round it at the 
sides. 

As soon as this is perceived, the furnace is to be 
opened, and the capsule drawn forward again, that it 
may stand for about the space of a quarter of an hour in 
a moderate heat to fine. Afterwards, the heat is again 
Increased as before, that the whole may enter into a 
smooth and thin fusion, and the whole matter stirred with 
a hook thoroughly heated, especially towards the sides 
of the capsule, so that the whole may be eciually mixed 
with the matter in fusion. 

When it is observed that the matter adhering to the 
hook runs ofi'quite thin;—that only a thin glassy pellicle 
is attached to the hook ; that the slags towards the sides 
of the capsule are liquid and clear like oil; that tho 
thick smoke has subsided ; that a clear leaden vapor be¬ 
gins to appear; and that, to appearance, no more than 
about half the Lead that was added remains in the cap¬ 
sule ; the fire for the assay is then to be raised. In the 
mean time, a small hemispherical ingot-mould is to be 
rubbed over with chalk ; the capsule is to be taken out 
of the fire, and tho work, as it is called, immediately 
poured into the ingot mould. 

Upon this the cupcllatiou must commence. During 
the scorification of the ore with Lead, two cupels must 
be inverted quite in the back part of the furnace, that 
their bottoms may become thorough red hot: this is 
called breathing tho cupels. When the scorification 
with lead is finished, the cupels being set upright in tho 
lurnace, are to be left there in the proper degree of 
heat, and the mouth of the furnace is to be closed again. 
The whole of the glass and scoria is then to be separa¬ 
ted from the work, which is to be hammered round. At 
the same time, a quantity of granulated Lead is weighed 
out, equal to that which has been used in the scorifica¬ 
tion, which lead is called the weigh-lead. 


38 


ASSAYING OF SILVER ORES. 


The work is to be put into one nnpel, nnd the weigh- 
lead into the other, and the same degree of heat is given 
to both, till the assay begins to look bright and clear ; 
the assay is then to be conducted a little more gently, 
but not so that it shall fix, of which the following are 
the most certain signs;—The appearance of a brown 
ring round the inside of the cupels | the vapor of the 
lead rising only a little above the brim of the cupel;—a 
bright circle, like oil, is at times perceived encompass-, 
ing the work; the appearance of several shining rays, at 
different intervals, round about the work. This degree 
of heat must be continued till the quantity is diminished 
to about half;—-after this, the fire must be gradually in¬ 
creased, till the button lightens. When this has taken 
place, the cupel is left in the furnace till the button is 
fixed, that it may not be divided into a number of small 
buttons, by being taken out too soon. 

As soon as the assay is become solid in the furnace, it 
is taken out, and the button immediately detached from 
the cupel by a stroke with the point of the cupel-tongs, 
before it adheres too fast. The same method is to be 
pursued with what remains of the weigh-iead in the 
other cupel. After this,*tho amount of the latter must 
be subtracted from that of the former, and the remainder 
only set down as the contents of the assayed quintal. 

The above mentioned cupellation of the mere weigh- 
iead, must bo undertaken at the same time, on account 
ot the fact, that nearly all Lead contains a small quanti¬ 
ty of Silver. By this means, the amount of Silver it con¬ 
tains is ascertained, and subtracted from the actual pro- 
<luct of the assay of the ore, to which it nocessarilv must 
have adhered from the Lead that,was added. 

Wash^ ores, which are interspersed in stones and ma¬ 
trices of ores, must bo previously freed from them as 
muc'h as possible ; then stamped tolerably line, washed, 
and roasted. An account having been taken of the lo.ss 
sustained by the ore in the washing and roasting, an as¬ 
say cwt. ol the roasted ore is to bo weighed out,—a ewt. 
of Glass of Lead, made by melting litharge with half its 
weight of calcined Hint, and twelve of granulated Lead 


TO ASSAY TIN. 


3D 

fire to be added to it. The process of scorification, and 
cupollation ore, are then conducted as usual. 

Refractory Silver Ores, which cannot be washed, must 
first be exposed for some time to a red heat, and roasted. 
Alter this, they are to be mixed with the very same in¬ 
gredients, and in the same proportion as has been men¬ 
tioned of the w^ash ores. They require a brisk lire in 
the fusion and scorification of them by Lead. The work 
thus obtained, is then to be cupelled. It often happens 
that melted metals contain a portion of Silver, and must 
bo assayed to knov/ wdiat proportion they contain. 

With this view, Regnlus of Antimony is scorified in a 
test or Capsule, in a very gentle heat, with eight or ten 
times its quantity of Lead, till the color of the fumes is 
altered, which in this case is usually brown, and the 
grey fumes of Lead appear, w’hen it is sufi'ered to stand 
.seven minutes longer. The Lead is then separated from 
the scoria, cupelled, and the Silver button weighed. 

'Zinc is calcined by itself in a crucible, and an assay 
cwt. of it scorified and cupelled with 2 cwt. of Glass of 
Le&d, and 12 of Lead. 

Bismuth is mixed wdth from four to six times its 
quantity of Lead; and in every respect treated like 
liegulas of Antimony; the fumes arising in the scorifi¬ 
cation of it by Lead, are only inclining to brown. 

To Asso.y Iron for Silver, To half an as.say cwt. of 
Iron, one cwt, of sulphur is to be added, and put into a 
capsule rubbed over on the iinsido wfith chalk, which after 
being covered with another, must be placed quite in the 
fore part of the assay-furnace, and roasted with a gentle 
heat. When the sulphur is expelled IVora it, the residue 
is weighed out. with eight times its wmight of Lead, for 
the assay, scorified in the capsule, and then submitted 
to cupellation. , 

The assay of Lead for Silver is easily conceived. If 
the Lead contains an ounce of Silver in the ton, it is con¬ 
sidered worth separating. 

To Assay Tin,, half an assay cwd. of it is to be added 
to tw'o cwt. of Lead. This is to be set forw'ard in the 
mouth of the furnace, so that it may become a little red. 
After a short time, the Tin covers the surface of the 


40 


TO ASSAY COPPER. 


Lead in the form of grey ealx. This gray calx or oxydo 
is to be taken off by little and little with an Iron ladle, 
and pushed towards the sides of the capsule till the 
whole is calcined. All the Oxyde of Tin collected 
together is to be mixed with an equal or twice 
the quantity of Glass of Lead, and again put into the 
furnace in a capsule. After which, a quantity of Lead 
is to be added to it, equal to ten times the weight of the 
Oxyde of Tin, and the whole to be scorified and cupel¬ 
led, like a refractory Silver ore. 

To Assay Copper^ half an assay cwt. of it is to be cupel¬ 
led with sixteen cwt. of Granulated Lead. 

The various sorts of Silver plate and coin, which dif¬ 
fer with regard to fineness, are to be assayed in the fol¬ 
lowing manner. The Silver is first to be rubbed upon 
the touchstone, and the marks compared with those of a 
known alloy, in order to obtain an approximation towards 
the proportion of Copper contained in it, so that the 
quantity of Lead to be added may be determined after¬ 
wards. 

This is done in the following manner : 

Silver twenty dwt. better than standard, or fine Silver, 
require three or four times its weight of Lead ; ten dwt. 
five or six times ; ten dwt. worse, eight or nine times •, 
twenty-five to forty dwt. worse, twelve or 13 times; two 
oz. fifteen dwt. to three oz. ; ten dwt. worse, thirteen 
nr fourteen times; four oz. five dwt. to five oz. worse, 
fourteen or fifteen times; eight oz. to nine oz. ten dwt., 
sixteen times ; and nine oz. ten dwt. 1o ten oz five dwt. 
worse than standard, twenty times its weight of Lead. 

The cupols being made hot. the Lead in the first place 
is put into them, and when this begins to circulate, the 
Silver is then added. With respect to the tire, the ope¬ 
ration must be regulated by the fineness of the Silver ; for 
the finer the assay is, the brisker the fire must be; and 
the more Copper there is contained in the assay, the lower 
the fire is to be kept. But all assays agree in this, that 
they all ought to be lighten hot, and especially fine Sil¬ 
ver, because it is very apt to fix before it is cleared of 
the other metals. In other respects, the process is the 
same as in common cupellations ; and tho small portion 


ANALYSIS OF DIFFERENT ORES. 


41 


of Silver contained in the Lead, must by no means bo 
omitted in the calculation^ 

ANALYSIS OF DIFFERENT ORES. 

I. Gold Ores. The presence of Gold may easily bo 
detected by treating the mineral supposed to contain it 
with Nitro-Muriatic Acid, and dropping muriate of Tin 
into the solution. If the solution contains Gold, a pur¬ 
ple precipitate immediately appears. 

Native Gold ought to be dissolved in Nitro-Muriatic 
Acid, the Silver, if any be present, falls to the bottom in 
the state of Muriate, and may be separated by filtration, 
and weighed. Pour Sulphate of Iron into the solution, 
and the Gold is precipitated in the Metallic state. The 
Copper, if any be present, may be precipitated by means 
of a plate of Iron. The presence of Iron may be ascer¬ 
tained by dropping tincture of Nutgalls into a portion of 
the solution. 

The Auriferious Pyrites may be treated with diluted 
Nitrous Acid, wdiich dissolves the Iron and separates tho 
Sulphur. Tho Gold remains insoluble, and is found in 
the state of small grains. 

II. Ores of Platina. The grains of crude Platina, which 
constitute the only ore of this metal, are exceedingly 
complex in their nature, containing not fewer than eight 
metals, and some times even more. These arc Mercury, 
Gold, Silver, Iron, Palladium, Rhodium, Osmium, and 
Iridum. 

The Mercury may be driven off by heat, and the Gold 
then becomes visible, and may be picket out, as it is in 
grains merely mixed with others. The Iron exists, in 
parts at least, in the state of Iron-sand, and may be sepa¬ 
rated by the Magnet. The portion combined with the 
Platina, if there be any such, is not so easily separated. 
The ore thus purified is mixed wdth diluted Nitro-Muri¬ 
atic Acid, which dissolves the rest of the Gold. Strong 
Nitro-Muriatic Acid, assisted by heat, dissolves ihe Pla¬ 
tina, the Palladium, and the Rhodium. The black pow¬ 
der and the metallic scales which remain undissolved are 
composed of Osmium and Iridum, which may be sepa- 


'12 


ANALYSIS OF DIFFERENT ORES, 


rated by the alternate aetion of Potash and Muriatic 
Acid. No good method is known of separating the por¬ 
tion of these metals, which dissolves along with the Pla- 
tina without loss. The Platina is precipitated by a 
concentrated solution of Muriate of Ammonia, and the 
Palladium by a solution of Prussiate of Mercury, The 
llhodium is obtained by adding common salt to the solu¬ 
tion thus freed from the other metals, evaporating to 
dryness, and digesting the dry mass in Alcohol, 

III, Ores of Silver. The analysis of the ores of Silver 
has been always considered as very important, on ac¬ 
count of the great value of the metal wdiich they contain 
in greater abundance, 

1 , Native Silver is to be dissolved in Nitric Acid, The 
Gold, if the ore contains any, remains in the state of a 
black powder, and may be dried and weighed. The 
Silver may be precipitated by common salt. One hun¬ 
dred parts of the precipitate dried denote about seventy- 
live parts of Silver, The presence of Copper may be 
ascertained by the greenish-blue color of the solution, 
and by the deep blue color which it assumes on adding 
Ammonia, The Copper may be precipitated by a plate 
•of Iron, or by the rules laid down hereafter. When the 
ore contains Ar.senic, its proportion may be estimated by 
weighing before and after liision ; for the Arsenic is dis¬ 
sipated by heat, or the ore may be dissolved as before in 
Nitric Acid, which acidifies the Arsenic, After the sepa¬ 
ration of the Silver, the Arsenic Acid ma}" be precipita¬ 
ted by Nitrate of Lead, 

2, Alloy of Silver and Antimony is to be treated with 
.Nitric Acid, which dissolves the Silver and oxydizes the 
Antimony. The Silver is estimated as above. The 
Oxyde of Antimony is to be dissolved in Muriatic Acid, 
and the metal thrown down by means of a plate of Iron, 

3, Sulphuret of Silver is to bo treated wPh diluted 
Nitric Atdd, which dissolves the Silver, lea^dng the 
greater part of the Sulphur untouched. The residue 
is to be dried, and then the Sulphur burnt off. The 
loss of weight gives the Sulphur The residue, if any, 
is undecomposed Sulphuret, to be treated as at first. 
The Silver is to be precipitated by common salt; and 


ANALYSIS OF DIFFERENT ORES. 


the other metals, if any bo present, may be ascertaincfl 
as above. Part of the Sulphur is always aoidilietl. 
The acid thus formed may be precipitated fiy Nitrate of 
Barytes; 100 parts of the dry preeipitato indicates 
about 14,5 of Sulphur, 

4. .dnthnoniated Silver Ore was anal^'scd as follows': 

t)no hundred parts of it were boiled in diluted Nitric 

Acid, The residue, washed and dried, was twenty-six. 
These twenty-,six were di^e.sted in Nitro-Muriatio Acid, 
The residue now weighcO thirteen, (so that thirteen had 
been dissolved) twelve of which were Sulphur, and 
burnt away, leaving behind them one part of Silica, 
The Nitro-Muriatio solution, when diluted largely with 
water, let fall a preeipitato which weighed thirteen (or 
ton of pure Antimony) and had the properties of O.xydo 
of Antimony; for they did not csuiporato till heated to 
ypdne,«,s, but at tliat temperature were di.ssipnted in a 
grey smoko, 

'I'he Nitric Solution was green. Common salt oeea- 
:sioned a precipitate which weighed 67,75, equivalent to 
d.'l.Sl of pure Silver. After the separation of this Mu¬ 
riate of Silver, Sulphate of Soda oeeasioiied no precijii- 
tato. Therefore the solution containing no Load, Whoa 
supersaturated with Soda, a grey preoipitate fell, weigh¬ 
ing five parts. On burning coals this preeipitato gav(» 
out an Ar.senhical smell. It was rodis,solved in Nitr'o 
Acid. Sulphurcted Alkali occasioned a smutty brown 
product; and Fru.ssio Alkali a Prussian-blue, which, after 
:sooriftcation, was raagnotic. Hence it was eonedudod 
that These live pans were a eorabinatiori of Iron and 
Avsenie Acid, 

The Nitric .solution which had been snporsaturatoil 
with Ammonia, was blue ; showing the preseneoof Cop¬ 
per. To diseover it more, it was saturated with Sulphu¬ 
ric Acdd, and put into it a polished plate of Iron. The 
ijuantity of Copper was so small that none could bo col¬ 
lected on the Iron, 

5 , Black Silver Ore may be analysed as No. S, .sepa¬ 
rating the Copper, if any bo present, by mean.s of an Iron 
plate, and estimating the cfarbonio acid that esoapas 
when the ore is heatoi or dissolved in Nitric Acid. 


41 


ORES OF MERCURY. 


6. Red Silver Ore has been analysed in the following 
manner: 

One hundred parts of it were digested in five hundred 
parts of Nitric Acid, previously diluted with water. The- 
nndissolved residue, being washed and dried, weighed 
42.06. Being treated with Muriatic Acid, it was all 
dissolved except 14.66 parts, which were Sulphur. The 
Muriatic solution, when diluted with a great quantity of 
water, deposited a white powder, which weighed 21.25, 
and was Oxyde of Antimony. The Nitric Acid solution, 
remained still to be examined. Muriatic Acid occasion¬ 
ed a heavy precipitate, which weighed 72.66 parts, and 
which was Muriate of Silver. Rc-agents showed that- 
the acid retained no other substance in solution. 

7. Chloride of Silver was analysed as follows : 

One hundred parts of it were mixed with thrice their 
weight of pure Carbonate of Potash, and melted together 
in a glass retort. The mass was dissolved in water, and 
tlie solution filtered. A residue remained, which was 
dissolved in Nitric Acid, with the exception of a red 
powder; which treated with Nitro-Muriatic Acid, was 
dissolved, except a little Chloride of Silver, which, when 
reduced, yielded 0.5 of pure Silver. Ammonia precipi¬ 
tated from the Nitro-Muriatic solution 2.5 parts of 
Oxyde of Iron. The Nitric Solution was precipitated 
by common salt; the Chloride of Silver thus obtained, 
yielded, when reduced, 67.25 of jiurc Silver. 

The original Aqueous solution of the Alkaline mass 
was saturated with Acotic Acid, on which it depositeil 
1.75 parts of Alumina. The solution was evaporated 
to dryness, and the dry mass treated with Alcohol, which 
dissolved the Acetate of Potash. The residue, amount¬ 
ing to 58.75 parts, was dissolved in water; and being 
treated with JNiuriatc of Caryta, fifteen parts of Sulphate- 
')f Carytes precipitated, indicating the presence of about 
e.5 of Sulphuric Acid, or 0.75 Sulphate of Potash, 'fho 
remaining fifty-eight parts were Muriate of Potash, in¬ 
dicating about twenty-one parts of Muriatic Acid. 

IV. Ores of Mcrcurij. 

1. Native Mercury and Amalgam may be dissolved in 
ISitric Acid. The Gold, if any present, remains in iho 


ORES OF COPPER. 


45 


v<tatc of powder, and may be estimated by its weight. 
The affusion of water precipitates the Bismuth, if the 
solution happens to contain any. Common salt precipi¬ 
tates the Silver, and also part of the Mercury; but the 
latter may be redissolved by a sufficient quantity of 
water, or, which is far better, of Oxy-Muriatic Acid, 
while the Muriate of Silver remains insoluble. Lastly, 
the Mercury may be precipitated by Sulphate of Iron, 
and estimated. Or the Mercury may be separated at 
once from the ore by distillation. 

2. Cinnabar may be dissolved in Muriatic Acid, as¬ 
sisted by the gradual addition of Nitric Acid. The 
Sulphur partly separates, and may be weighed, and is 
partly converted into Sulphuric Acid; which may be 
separated by Muriate of Carytes, and the portion of 
Sulphur ascertained. The Mercury may be separated 
by distilling a portion of the ore with half its weight of 
Iron filings. 

3. The analysis of the Hepatic ore is conducted in a 
similar way. The small portion of foreign bodies are to 
be ascertained by the processes already laid down. 

4. Muriate of Mercury may be digested in Muriatic 
Acid till the whole is dissolved. Muriate of Carytes 
precipitates the Sulphuric Acid, one hundred parts of 
which are equivalent to one hundred and eighty-six of 
Sulphate of Mercury ; and the proportion of this salt 
being known, we have that of the Muriate. Or, per¬ 
haps, a better mode of analysis would be to boil the .salt 
with Carbonate of Potash till it is decomposed. 

V. Ores of Copper. 

1. Native Copper sometimes contains Gold, Silver, or 
Iron. It may be dissolved in Nitric Acid ; the Gold re¬ 
mains in the state of a blackish or rather violet-colored 
powder; the Silver may be separared by a polished plate 
of Copper, (or it may be precipitated from a separate 
portion of the solution by common salt.) The Iron may 
be separated by boiling the solution to dryness, and 
treating the residue with water. By this process, the 
Nitrate of Iron is decomposed; the Oxyde of Iron re¬ 
mains, while the water dissolves the Nitrate of Copper. 
The last salt may be decomposed by boiling it with Pot- 


46 


ORES OF IRON. 


fish ; the precipitate, dried in a red heat, is Black Oxyde 
nf Copper, One hundred part,s of it denote eighty ol 
Metallic Copper. 

2. Sulphurate of Copper may bo dissolved in Muriatic 
Acid by the help of Nitric Acid. Part of the Sulphur 
separate.^, part is acidiiicd. The solution being divided 
into two parts; from the one the Copper may be pre¬ 
cipitated by an Iron plate, and from the other the Iron 
by Ammonia. The varigated Copper ore, and Copper 
Pyrites yield to the same mode of analysis 

*3. Orey Ore of Copper was analyzed as follows : H 
was heated to redness in a retort, tne Sulphur and Arse; 
nic were driven off. The Sublimate, being weighed, 
was digested in Potash,, which separated the Sulphur, 
and lel't the Arsenic. The ro.sted ore was then dissolved 
in Nitric Acid, except a small portion which yielded to 
Muriatic Acid. The solution being mixed, 'a little 
muriate of Silver fell, which was separated, and reduced. 
The solution, mixed with Sulphuric Acid, was evapo¬ 
rated to drynes.s, and redissolvcd in water. Amlnphi^ 
tlirewdown the Iron from this solution, and a plate of 
Zinc the Copper. 

4. lied Copper Orr has only to bo dissolved in Muri¬ 
atic Acid, and the Copper precipitated by a plate of 
Iron; eighty-eight parts of the precipitated Copper 
being ec^^uivalent to one hundred of the Orange Oxyde of 
which the ore is composed. 

5. The analysis of the Oxydes and Carbonates of Copper 
scarcely rcquire.s any remarks. The water and Carbonic 
Acid must be estimated by disti>’ation in close vessels, 
and collecting the jmoducts. 1 he ore may then be di.*:;- 
solved in a Nitric Acid, and its Copper ascertained as 
above. 

(). Arseniatc of Copper. The ore to be di.ssolved in 
diluted Nitric .’,.cid, and Nitrate of Lead poured in. The 
.solution was evaporated till a precipitate began to ap¬ 
pear, and then mixed with alcohol, ArSibiuate of Lead 
precipitated, 1 00 parts of this salt indicate 83 of arsenic. 
Tlie Copper M'as separated from the Nitric Acid, by 
boiling it with potash. 

VI. Ores of Iron. Notwithstanding the great variety 


SOLDERING FOR IRON. 


47 


of Iron ores, they may be all, as far as analysis is con¬ 
cerned, arranged under three heads, namely— 1 . Sul- 
phupets ; 2 , Oxydes ; and 3. Salts. 

1 / Pyrites.^ or sulphiireted Iron, may be treated with 
boiling Nitric Acid, till the Sulphur is acidified. Muri- 
Q;tic Anid is then to be added, and the digestion continued 
till the whole be dissolved. Muriate of Carytes is then 
to be added to precipitate the Sulphuric Acid. 100 of 
the dried precipitatQ ^dicates 14.5 of Sulphur, If tho 
solution contains only, Iron,- it may bo precipitated by 
Carbonate of Soda, «cab>mcd to redness, and weighed. 
But if earths or manganese be present, we must proceed 
by the rules laid clo wn in the section of analysis of earths 
and stones, - 5 ^ 

2. If the dxydes of Iron be pure, that is to say, con¬ 
tain nothing |but.j[con, wo have only to dissolve them in 
Muriatic Aoi^,jand precipitate them as above. But it is 
very seldom. ores possess this perfect degree of ])u- 
rity, The.ln^^is usually combined vrith manganese-i 
alumina, sil]c|,„-*or with all of these together. Tho analy^ 
sis is to be copducted exactly accofding to the rules lai^ 
down in’ the section above mentroned, 

3;. The sparry d-ron analysed in the same 

manner, excepting only tha]^ tlj^ Carbonic Aciil-gaa must 
be separated by distillation or. solution -in close vessels, 
and estimated by, thejfult^,laid' (fe>wn* _ . . < , > . 

4. /repr is ^naly>ed aa;^b)lQw:^ ^ 

■ 100 parts jof it to be boil^jd.wijlli d?jot^sh4ilj^j^ijp.,4’'i^b*^^®: 
Acid is separated. , ^Nitrate of^^ad ps^mixe^yi^tintbey 
solution; 100 parts of the precjpitjije •indiyatgs^33 of, 
Arsenic Acid, That por|i©ii ofithe<or^->vhich eluded tho^ 
action of the Potash is tre.^tgd;\y^h']\^jLiriatic Acid ; thof 
undissolvcd residue is Si.|ig^, /•^Tijp.lVfuriatic Acid, to bo- 
super-saturated with Ammpniai The,Iron is precipita-j 
ted, but the Coppe/’ is dissjj^vejd • 

SOLDERING PdR’ IRON.' ‘' ! 

• f' , ' iP- , J 

. Melt the filings oll^spft cast Iron dn^a^. e|;U 9 ,ible with 

Borax, prfvimisly A^lcined, and a ha^<4 

pitch-like soJdering §iubstance 'is obtained) Wing. Glasfj 

of Bbrax,'*cblor(?dTracTs^with Iron,*”‘ 


48 


ORES OF TIN. 


Sal-ammoniac having been applied to the internal 
joining, or between the overlapped edges of thin sheet 
Iron, some of this solder being powdered, is to laid along 
a short portion of the joint, and as soon as it is melted 
over a clear forge fire, the soldered part is to be placed 
on the beak of an anvil, and beaten with a light hammer 
and quick hand, as long as the heat permits. More of 
the powder is then to be laid upon the joining part of 
the joining, until the whole of the seam is soldered.— 
Another method, is to melt five ounces of Borax in an 
earthen crucible, and when melted, to add half an ounce 
of Sal-ammoniac, and pour the melted matter upon an 
Iron plate. When cold, it will appear like a glass, and 
is to be powdered and mixed with an equal quantity of 
unslacked lime. 

The Iron or Steel being heated to a red heat, a little 
of the above powder is to bo sprinkled on the surface, 
where it will melt like sealing-wax. The Iron or Steel 
is then to be again heated, but considerably below the 
ordinary welding heat; then brought to the anvil, and 
hammered until the surfaces are perfectly united. 

VII. Ores of Tin. 

1 . The Sulphuret of Tin was thus analysed : 120 
parts of the ore digested with Nitro-Muriatic Acid ; 43 
parts remained undissolved. Of these, 30 burnt away 
with a blue flame, and were sulphur ; of the remaining 
13, eight dissolved in Nitro-Muriatie Acid. The undis¬ 
solved five were heated with wax, and yielded a grain of 
Iron attracted by the magnet. The rest was a mixture 
of Alumina and Silica. The Nitro-Muriatic solution 
was completely precipitated by Potash, and the precipi¬ 
tate re-dissolved in Muriatic Acid. A cylinder of Tin 
precipitated 44 parts of Copper from the solution, and 
lost itself 89 parts of its weight. A cylinder of Zinc pre¬ 
cipitated 130 parts of Tin ; so that deducting the 89 
parts of Tin dissolved during the precipitation of the 
Copper, 41 remain for the Tin contained in the ore. 

2 . Tin-stone was thus analysed ;—100 parts of the ore 
were heated to redness, with 600 parts of Potash, in 
a Silver crucible; and the mixture being treated with 


OBES OT LEA». 


4i 


’r^irjn Trater, .eleven parts remained imdissolved. These 
.elevei\, by a repetition of the treatment with Potash, 
were r-educed to This small residue dissolved in 

Muriatic -^eid. Zino precipitated from the solution one 
half part of the Tin. and the Prussinn. Alkali i>avc a 
blue precipitate, which indicated one-fourth part of Iron. 


The Alkaline 


solution was saturated with Ainriatic - 


Acid, a white jirecipitatc appeared, but it\\as redissolved 
'by addiuo- more Acid, The whole was ])recii)itatc(' by 
Carbonate of Soda. The precipitate, liich Inid a yel¬ 
lowish color, was redissolved in Aluriatic Acid, and a 
Cj’lindar of Zinc bein^ inserted into the solution, seventy- 
seven of Tin were obtained, indicating nearly ninety- 
nine parts of Oxyde of Tin. 

VlII. Ores of Lead. 

1. Sulphate of Lead itsnally contains a little Silver, 
and sometimes also Antimony and Zinc. It may be 
treated with diluted A'itric Acid, which leaves ouiy the 
Sulphur undissoived, the weight of which is to betaken, 
and its purity determined by comlnistion. If Antimony 
be present, it will either remain in tlic state of White 
Oxyde, or, if dissnived. it will be precipitated by diluting- 
the solution with water, Aluriatie Acid is to 1)C addeii. 


and the solution evaporated till it is reduced to a small 
portion. Muriate of Lead and of Silver precipifale. 
The fir.st of these may be dissolved in boiling water, the 
second remains insoluble. The muriate of Silver may I’e 
separated by digesting the precipitate with Ammonia. 
The liquid Irom which the Muriates were separated may 
contain Iron, Zinc, and Copper. The Iron may be pre¬ 
cipitated by Ammonia added in excess; the Cojiper, by 
a plate of Zinc ; the Zinc may be precipitated l:y Car¬ 
bonate of Soda, reduced to the Tdetailic stale, and 
weighed, snbstracting vrhat has been separated Irom the 
plate of Zinc. 

2. Arseniaied Lead. One hundred parts roasted for 
half an hour, and occasionally treated with a little Tallow 
it lost thirty-eight parts, which are considered as Oxyde 
of Arsenic. The residue was treated with concentrated 
Muriatic A^id, and boiled in it for a quarter of an hour. 


ORES or EEA». 


^0 

The liquid assumed a red color, and emitted abundance 
of Chlorine Gas. A white needle-form salt was de¬ 
posited, and some of it was obtained by evaporation. 
•This salt, dissolved in water, and treated with Sulphate 
of Soda, yielded twenly-fiv^e parts of Sulphate of Lead, 
= 20.2 parts of Lead. The liquor thus freed from Lead 
was treated with Ammonia. The precipitate obtained 
weighed thirty-nine parts. It consisted of Oxyde of 
Iron mixed with Oxvde of Arsenic. The production of 
Chlorine is considered Lead to be in a state of Peroxyde,- 

3. Carbonale of Lead. One hundred grains were 

thrown into two hundred grains of Nitric Acid, diluted 
with three hundred grains of water. It dissolved com¬ 
pletely with elfervescence. The loss of weight was six¬ 
teen grains. It was equivalent to/the Carbonic Acid. 
The solution, which was colorless, was diluted with 
water, and a cylindar of Zinc put into it, in twenty-four 
hours the Lead was pi*ecipitated in the JMetallic state. 
It weighed seventy-seven grains ; = eighty-twm grairrs 
Oxyde. . 

If Muriatic Acid be separated, it may be easily de¬ 
tected, and its weight ascertained by means of Nitrate 
of Silver. 

4. Sulphate of Lead. One hundred grains of the ore 
heated to redness, lost two grains, which were consider¬ 
ed as water. It was then mixed wdth four hundred gr. 
of Carbonate of Potash, and heated to redness in a Pla- 
tina crucible. The reddish yellow mass thus obtained 
was digested in water, and the whole thrown on a filter. 
The Oxyde of Lead thus obtained weighed seventy-two 
grains. 11 was dissolv’ed in diluted Nitric Acid. One 
grain of Oxyde of Iron remained behind. Into the solu¬ 
tion a cylindar of Zinc was put. The Lead thrown dowm 
weigheil sixtv-six and a half ii rains. The Alkaline 
solution was supersaturated with Nitric Acid, and then 
treated with Acetate of Carytes. The Sulphate of Carytes 
obtained weighed seventy-three grains, indicating twenty- 
five grains of Sulphuric Acid. 

5., Phosphate of Lead., was then analysed. One hun¬ 
dred grains were dissolved in diluted Nitric Acid. Ni- 
1 trate of Silver dropped into the srolution formed a pr^- 


6fR«s oy nicerl. 


. 51 

cipita'te -vreighinsi eleven grains, = 1.7 grains Muriatic 
Acid. The solution was mixed with Sulphuric Acid. 
The Sulphate of Lead precipitated weighed one hun¬ 
dred and six grains, = 78.4 Oxyde of Lead. The 
solution was freed from Sulphuric acid by means of Ni¬ 
trate of Carytes, and then almost neutralized with Am¬ 
monia. Acetate ol Lead was then dropped in. The 
phosphate ol Lead which precipitated weighed 82 grains 
= 18.37 Phosphoric Acid. The solution was now mixed 
with IMuriatic Acid, evaporated to dryness, and the dry 
mass washed in Alcohol, when evaporated, left a small 
residue, which dissolved in water, and formed Prussian 
blue with Prussiate of Potash, It containad about 1.10 
grain of Oxyde of Iron. 

6. Molybdate, of Lead. The ore was boiled repeat¬ 
edly with Sulphuric Acid, till the Acid refused to dis¬ 
solve any rhore. The solution contained the Molybdic 
Acid. The undissolved powder, (Sulphate of Lead) 
was boiled for an hour with Carbonate of Soda, and then 
w^ashed. Nitric Acid now dissolved it, except a little 
Silica. The Lead was precipitated from this solution by 
Sulphuric Acid; after which Ammonia separated a little 
Oxyde of Iron, The Sulphuric Acid solution was di¬ 
luted with sixteen parts of water and saturated with 
‘Ammonia; a little Oxyde of Iron gradually precipita¬ 
ted. The solution was now evaporated to dryness, and 
the mass strongly heated to separate the Sulphate of 
Ammonia. The residue repeatedly treated with Nitric 
Acid, was converted into yellow Molybdic Acid. 

IX. Ores of Nickel .—No exact method of analysing 
the ores of Nickel has yet been published. 

1. Copper Nickel may be dissolved in Nitrio Acid, by 
which the great part of the Sulphur will be separated. 
The Arsenic may be afterwards precipitated by the 
affusion of water. A plate of Iron will expel the Cop¬ 
per, if any be present. Precipitate by Potash added m 
excess, and boil the precipitate, which will separate the 
Arsenic and Sulphur completely. Dissolve the precipi¬ 
tate (previous exposed moist for some time to the airj in 
Acetic Acid, and add an excess of Ammonia. Ther Iron 
is precipitated; bat the- Cobalt and -Nickel -remain in 


fi!i. IXTRA.CTloa X3F QUICKSILTBR- 

solution. Evaporate, and the Cobalt is deposited-, then 
by continuing the evaporation to dryness, the Nickel is 
obtained. 

X. Ores of Zinc. 

1 Blende may be treated with diluted Nitric Acid, 
Mrhich will separate the Sulphur, the Siliceous gangue, 
&c. The purity of the Sulphur is to be ascertained by 
combustion, and the residue analysed as above described. 
Precipitate the Nitric solution by Soda, redissolve in 
Muriatic Acid, precipitate the Copper (if any be present) 
by a plate of Iron -, separate the Iron by adding an excess 
ot' Ammonia. The Zinc now only remains in the solu¬ 
tion, which may be obtained by evaporating to dryness, 
redissolving in Muriatic Acid, and precipitating by Soda. 

2, Calamine may be digested in Nitric Acid, noting 
the loss of weight for Carbonic Acid, and the insoluble 
residue boiled with Muriatic Acid repeatedly; what rer 
mains after dilution with boiling water is Silica. The 
Nitric solution contains Zinc, and probably also Iron 
and Alumina; evaporate to dryness, redissolve, and add 
an excess of Ammonia. The Iron and Alumina either 
remain undissolved or are precipitated, and they may be 
separated by Potash. The Zinc may be preipitated by an 
Acid, or by evaporation to dryness The Muriatic solur 
tion probably contains Iron and Alumina, which may be 
precipitated by the rules already laid down. 

MERCURY OR QUICKSILVER.—EXTRACTION 

OF ITS ORES. 

This metal is distinguished by its fluidity at common 
temperature; its density, 13.6, its Silver-blue lustre, and 
its extreme mobility. A cold of 39® below Zero of 
Fahrenheit, or 40® Cent., is required for its congelation, 
in which state its density increased in the proportion of 
ten to nine, or it becomes of specific grav. 15.0. At a 
temperature of 656® Fahrenheit, it boils and distils off in 
an elastic vapor; which, being condensed by cold, forms 
purified Mercury. 

Mercury combines with great readiness with certain 
metals, as Gold, Silver, Zme, Tin, and Bismuth, forming, 


MURIATKD MXRCURT. ■ ' ' 55' 

in certain proportions, fluid solutions of these metals or 
amalgam. This property is extensively employed ii) 
many arts; as in extracting Gold and Silver from their 
Ores. 

The Mercurial Ores may be divided into four species. 

1. Native Quicksilver, it occurs in most of the mines 
of the other Mercurial Ores, in the form of small drops, 
attached to the rocks, or lodged in the crevices of other 
ores. 

2. Argenial Mercury., or Native Silver Amalgam. It 
has a Silver-white color, and is more or less soft,^ac¬ 
cording to the proportion which the JMercury bears tp 
the Silver. Its densitv is sometimes so high as fourteen. 
A moderate heat dissipates the jMercury, and leaves the 
Silver. It occurs crystallized in a variety of forms. 

3. Sulphuret of Mercury., commonly called Cinnabar, 
is a red mineral of various .shades ; burning at the blow¬ 
pipe with a blue flame volatilizing entirely with the smell 
ol burning Sulphur, and giving a Quicksilver coating to 
a plate of Copper held in the fumes. Even the powder 
of (flnnabar rubbed on Copper whitens it. Its density 
varies from C.9 to 10.2 It becomes negative electric by 
friction. 

Jl Bituminous Sulphuret of Mercury appears to be the 
base of the great exploration of Idria; it is of a dark 
liver-red hue, and of a slaty texture, with straight or 
twisted plates. It exists in large masses in the bitumi¬ 
nous schists of Idria. Sometimes the ore includes im¬ 
pressions of fishes, curiously spotted with Cinnabar. 

The compact ore seems very complex in composition, 
as shown by the following analysis,—Mercury, 81.8, 
Sulphur, 13.75; Carbon, 2.3; Silica, 0.65; Alumina, 
0.55; Oxyde of Iron, 0.20; Copper, 0.62; water, 0.73, 
in 100 parts. At Idria and Almaden the sulphurets are 
extremely rich on Alercury. 

4. Muiiated Mercury., or the Chloride of Mercury, 
commonly called Horn Mercury This ore occurs in 
very small crystals of a pearl-grey or greenish-grey 
color, or in small ripples which stud, like crystals, the 
cavities, fissures, or leodes among the ferruginous. 
I^angues of the other ores of Mercury. It is brittle, and 


?54 MKTALL^RfflC TRKATWKW’f ^'F QTJlCKSlLYKlt. 

entirely volatile at the blow-pipe, characters which dis- 

- tin"tiish it from horn Silver. 

The ffeoloirical position of the mercurial ores, in all 
parts of the world, is in the strata which commence th6 
series of secondary formations. Sometimes they arc 
found in the red sand stone above the coal. They occur 
also among the strata below, or subordinate to the cal- 
. careous formation, called zechstein^ in Germany, or 
among the accompanying bituminous schist; and lastly, 
they form masses tn Ihe zechstein itself. Thus, it ap¬ 
pears that the mercurial deposites are confined within 
very narrow geological limits, between the calcarious 
beds of zechstein, and the red sand stone. They appear 
" at times in carbonaceous nodules, derived from the de¬ 
composition of mosses of various kinds; and the whole 
mercurial deposit is occasionally covered with beds of 
charcoal. 

They are even sometimes accompanied with the re¬ 
mains of organic bodies, such as casts of fishes, fossil 
shells, silicified wood, and true coal. 

Mercury is, generally speaking, a metal sparingly 
distributed in nature, and its mines are very rare. The 
mine of Idria, in Triuli, in the county of Goritz, took fire 
in the year 1803, which was most disastrous to the mines. 
It was extinguished only by drowning all the under¬ 
ground workings. The sublimed Mercury, in this ca¬ 
tastrophe, occasioned diseases and nervous tremblings to 
' more than 900 persons in the neighborhood. 

The metallurgic treatment of the Quicksilver ores is 
tolerable simple. In general, when the sulphuret* of 
mercury, the most common ore, has been pulverized, and 
sometimes washed, it is introduced into retorts of cast 
iron, sheet iron, or even stone ware, in mixture with an 
equal weight of quick-lime. These retorts may be ar¬ 
ranged in various ways. 

At first, earthen ware retorts were employed in the 
furnaces; but they were succeeded by iron retorts. 

There exist three kinds of apparatus for distilling 
Mercury. 1st. The furnace called a gallery: 2. The 
furnace with alwiels; and 3. The large apparatus of 

- .Idria. • . 


' •F -rntWACKs. ' 






1 st. Furiiace called Gallery of the Palatinate Tt con¬ 
sists ol four ranges, a a. h b. of large retorts, styled ctt- 
curbits, of cast iron, in which the ore of Mercury is sifb- 
jected to distillation. This arrangement is shown in Fig. 
1 , which presents a vertical section in the line a 6 of the 
ground plan, Fig, 2, In insjiecting these plans, the 
idea ma}' be easily formed of its construction. 

Such a furnace includes commonly 30 cucurbits, and 
sometimes 52. Into each are introduced from 5G to 70 
pounds ot ore, and 15 to 18 pounds of quicklime, a mix¬ 
ture which fills no more than two-thirds of the cucurbit: 
to the neck a stone ware receiver is adapted, containing 
water to half its height. The fire, at first moderate, is 
eventually pushed till the cucurbits are red hot. The 
operation being concluded, the contents of the receivers 
are poured out into a wooden bowl placed upon a plank 
above a bucket; the.Quicksilver falls to the bottom of the 
bowl, and the water draws over the Black Mercury, for 
so the substance that coats the inside of the receiver is 
Called. This is considered to be a mixture of sulphuret 
and oxyde of Mercury. 

The Black Mercury, taken out of the tub and dried, is 
istilled anew with excess of lime ; after which the resi¬ 
due in the retorts is thrown away, as useless. This first 
mode of distilling Quicksilver, as the most simple, may 
serve lor the beginner in the business, without describ¬ 
ing the other furnaces. 

Quicksilver may be most readily extracted from Cinna¬ 
bar, by heating it in contact with quick-lime. 

In some places, hammerschlay, or the iron cinders 
driven off from the Bloom by the tilting hammer, has 
been used instead of lime in the reduction of this mercu¬ 
rial ore, whereby Sulphurous Acid and Sulphuret of Iron 
is formed. 

To obviate all inconveniences and losses of furnaces on 
a large scale, the proper chemical arrangements suited 
to the present improved state of arts ought to be adopted, 
by which labor, luel, and Mercury might all be econo¬ 
mized to tho utmost extent. The only apparatus fit to 
be employed aright is a series of cast iron cylinder re¬ 
torts, somewhat like those employed in the coal - gas 


or ru»KAC*». 


■^"ork*. but with peculiarities suited to the condensation 
of the mercurial vapors.. Into each of these retorts, 
suppose to be at least one foot square in area, and 7 feet 
lonir, G or 7 cwts. of mixture of the ground ore with the 
quick-lime, may he easily introduced, iVom a measured 
heap, by means of a shovel. The specific oravity of the 
cinnabar being more than six times that of water, a cubic 
foot of it will weigh more than hfo cwts.: but supposing 
the mixture of it with quick-lime (when the ore does not 
contain the calcareous matter itself) to be only thrice 
the density of water, then four cubic feet might be put 
into each of the above retorts, and still leave 1}-^ cubic 
feet of empty space for the expansion of volume which 
may take place in the decomposition. The ore should 
be certainly linely ground, by stamps, iron cylinders, or 
edge wheels, so that, when mixed with quickrlime, the 
cinnabar may be brought into immediate contact with 
its decomposer, otherwise much of it will be dissipated 
unproductively in fumes, for it is extremely volatile. 

The one extremity of the retort is covered by a lid 
fastened by screw-bolts, which is removed in charging 
and discharging the retort, at the other extremity is con¬ 
nected, as before, with the retort, a downward bent tube, 
terminating in a trough with a current of water, to keep 
it constantly cool, the trough being a little inclined to 
make the condensed mercury to collect at one end, Ifora 
where it might be drawn off by stop-cocks, &c. 


MEASURE OF LENGTH.—FRENCH AND 
ENGLISH. 


Millimetre.03937. English Inches. 

Centimetre .39371. “ “ 

Decimetre .3.93710. 

Metre.39.37100. “ “ 

Mil’s. Fur. Yd’s. F’t. In. 
Decametre... .393.71000, 0. 0. JO. 2. 9.7 


Hecatometre 3937.10000^ 0. 0. 109. 1. 1.. 

•Kilometre...39371.00000. 0. 4. 213. 1. 10.2 

Myriometre393710.00000. 6. 1. 156. 0. 6. 


CAPACITY. 


Cuh. Inch. 

Milliliter...,. .06103. 

Centiliter. .61028. English. 

Deciliter.61.0280. Tons. Hhds. W. Gals. Pts. 

Liter.61.02800. 0. 0. 0. 2.1133 

Decaliter.610.28000. 0. 0. 2. 5.1352 

Hectolitre.., .6102.80000. 0. 0. 26.419. 

Kilolitre.61028.00000. 1. 0. 12.19. 


Miriolitre.. 610280.00000. 10. i. 58.9. 














5B 


TABLS or IfSTRCf. 


WEIGHT.—ENGLISH GRAIN. 


Milligramme.0154. 

Centigramme.1544. 

Decigramme. 1.5444. [^votrdupots.] 

Gramme. 15.4440. Lbs. Ounce. Dram. 

Dicegramme .154.4402. 0. 0. 5.65 

Hectogramme.1544.3402. 0. 3. 8.5 

Kilogram rite, ..15444.0234. 2. 3. 5. 

Mirogramme........154440.2344. 22. 1. 2. 


METRES. 


1 . Myrametre.10000. 

1. Kilometre.1000. 

1. Hectometre.100. 

1. Decametre.10. 


METRE. 

1. Metre. : .'.1. 

1. Decimetre.0.1. 

1. Centimetre.0.01. 

1 . Millimetre.O.OOI. 


For square dimensions, the Metre or its parts are em¬ 
ployed. When used for measuring Land the term Are 
is adopted, which is a Decimetre Squared, a Hectare, or 
one hundred Acres, is about equal to two English Acres. 

For the integer of the measure of Capacity, the Cubed 
Decimetre is employed under the name of Litre, which 
is about equal to 2j^ English Wine.Pint. . 

For the measure of weight of a Cube Centimetre of 
distilled water at 32® F. has been adopted, it is called 
Gramme, and is equal to 15.4 English grains. 

























